mashmallow or pydantic models from json-schema

Apologies if this already discussed somewhere - I am new to this project. To get started I used `cfn2py` script and tested some round-trip serializations back to json and yaml using some `deepdiff` and `cfn-lint` checks.

One concern is that boolean values are not JSON booleans but strings. Why does the `t.to_dict()` and `t.to_json()` data contain strings instead of JSON booleans? It seems like `encode_to_dict(obj)` should be replaced with just a `json.loads(json.dumps(obj))` and let the `json` lib take care of all the necessary python/JSON compatibility and encodings.

Or using marshmallow or pydantic models in general should take care of all the schema mappings and serializations. It might also be easier to use botocore service descriptions or other AWS json payloads to auto-generate json-schema and models. It's not quite the same thing as CFN templates, but botocore has service API descriptions in e.g. `lib/python3.7/site-packages/botocore/data/cloudformation/2010-05-15/service-2.json`; see also
- https://pydantic-docs.helpmanual.io/datamodel_code_generator/
- https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/cfn-resource-specification.html
- https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/resource-type-schemas.html

The resource-type-schemas might be amenable to auto-generation of service models using mashmallow or pydantic schema parsers and code generators. If something like this were to work well, it might eliminate most if not all of the issues about supporting new features in CFN services.

In this example, the `cfn_schemas` is a directory with unzipped data from a regional download .zip file.
```console

pip install datamodel-code-generator[http]

wget https://schema.cloudformation.us-east-1.amazonaws.com/CloudformationSchema.zip
mkdir cfn_schemas
mv CloudformationSchema.zip cfn_schemas/
cd cfn_schemas/
unzip CloudformationSchema.zip
cd ..
datamodel-codegen --input cfn_schemas/aws-s3-bucket.json --input-file-type jsonschema --output aws_s3_bucket.py
cat aws_s3_bucket.py
```

The pydantic models have built in serializations.

The resulting `aws_s3_bucket.py` contains:

```python
# generated by datamodel-codegen:
# filename: aws-s3-bucket.json
# timestamp: 2021-03-11T02:07:54+00:00

from __future__ import annotations

from typing import List, Optional

from pydantic import BaseModel

class DefaultRetention(BaseModel):
Years: Optional[int] = None
Days: Optional[int] = None
Mode: Optional[str] = None

class ReplicationTimeValue(BaseModel):
Minutes: int

class FilterRule(BaseModel):
Value: str
Name: str

class AccelerateConfiguration(BaseModel):
AccelerationStatus: str

class Metrics(BaseModel):
Status: str
EventThreshold: Optional[ReplicationTimeValue] = None

class RoutingRuleCondition(BaseModel):
KeyPrefixEquals: Optional[str] = None
HttpErrorCodeReturnedEquals: Optional[str] = None

class DeleteMarkerReplication(BaseModel):
Status: Optional[str] = None

class OwnershipControlsRule(BaseModel):
ObjectOwnership: Optional[str] = None

class CorsRule(BaseModel):
ExposedHeaders: Optional[List[str]] = None
AllowedMethods: List[str]
AllowedOrigins: List[str]
AllowedHeaders: Optional[List[str]] = None
MaxAge: Optional[int] = None
Id: Optional[str] = None

class AccessControlTranslation(BaseModel):
Owner: str

class ObjectLockRule(BaseModel):
DefaultRetention: Optional[DefaultRetention] = None

class S3KeyFilter(BaseModel):
Rules: List[FilterRule]

class Destination(BaseModel):
BucketArn: str
BucketAccountId: Optional[str] = None
Format: str
Prefix: Optional[str] = None

class RedirectAllRequestsTo(BaseModel):
Protocol: Optional[str] = None
HostName: str

class TagFilter(BaseModel):
Value: str
Key: str

class PublicAccessBlockConfiguration(BaseModel):
RestrictPublicBuckets: Optional[bool] = None
IgnorePublicAcls: Optional[bool] = None
BlockPublicPolicy: Optional[bool] = None
BlockPublicAcls: Optional[bool] = None

class NoncurrentVersionTransition(BaseModel):
StorageClass: str
TransitionInDays: int

class ServerSideEncryptionByDefault(BaseModel):
SSEAlgorithm: str
KMSMasterKeyID: Optional[str] = None

class MetricsConfiguration(BaseModel):
TagFilters: Optional[List[TagFilter]] = None
Id: str
Prefix: Optional[str] = None

class ObjectLockConfiguration(BaseModel):
ObjectLockEnabled: Optional[str] = None
Rule: Optional[ObjectLockRule] = None

class LoggingConfiguration(BaseModel):
DestinationBucketName: Optional[str] = None
LogFilePrefix: Optional[str] = None

class Tiering(BaseModel):
AccessTier: str
Days: int

class DataExport(BaseModel):
Destination: Destination
OutputSchemaVersion: str

class ReplicationTime(BaseModel):
Status: str
Time: ReplicationTimeValue

class RedirectRule(BaseModel):
ReplaceKeyWith: Optional[str] = None
HttpRedirectCode: Optional[str] = None
Protocol: Optional[str] = None
HostName: Optional[str] = None
ReplaceKeyPrefixWith: Optional[str] = None

class EncryptionConfiguration(BaseModel):
ReplicaKmsKeyID: str

class InventoryConfiguration(BaseModel):
Destination: Destination
OptionalFields: Optional[List[str]] = None
IncludedObjectVersions: str
Enabled: bool
Id: str
Prefix: Optional[str] = None
ScheduleFrequency: str

class ReplicationRuleAndOperator(BaseModel):
TagFilters: Optional[List[TagFilter]] = None
Prefix: Optional[str] = None

class VersioningConfiguration(BaseModel):
Status: str

class CorsConfiguration(BaseModel):
CorsRules: List[CorsRule]

class ReplicaModifications(BaseModel):
Status: str

class Transition(BaseModel):
TransitionDate: Optional[str] = None
TransitionInDays: Optional[int] = None
StorageClass: str

class SseKmsEncryptedObjects(BaseModel):
Status: str

class Tag(BaseModel):
Value: str
Key: str

class AbortIncompleteMultipartUpload(BaseModel):
DaysAfterInitiation: int

class SourceSelectionCriteria(BaseModel):
ReplicaModifications: Optional[ReplicaModifications] = None
SseKmsEncryptedObjects: Optional[SseKmsEncryptedObjects] = None

class OwnershipControls(BaseModel):
Rules: List[OwnershipControlsRule]

class RoutingRule(BaseModel):
RedirectRule: RedirectRule
RoutingRuleCondition: Optional[RoutingRuleCondition] = None

class NotificationFilter(BaseModel):
S3Key: S3KeyFilter

class ServerSideEncryptionRule(BaseModel):
BucketKeyEnabled: Optional[bool] = None
ServerSideEncryptionByDefault: Optional[ServerSideEncryptionByDefault] = None

class ReplicationDestination(BaseModel):
AccessControlTranslation: Optional[AccessControlTranslation] = None
Account: Optional[str] = None
Metrics: Optional[Metrics] = None
Bucket: str
EncryptionConfiguration: Optional[EncryptionConfiguration] = None
StorageClass: Optional[str] = None
ReplicationTime: Optional[ReplicationTime] = None

class Rule(BaseModel):
Status: str
NoncurrentVersionExpirationInDays: Optional[int] = None
Transitions: Optional[List[Transition]] = None
TagFilters: Optional[List[TagFilter]] = None
NoncurrentVersionTransitions: Optional[List[NoncurrentVersionTransition]] = None
Prefix: Optional[str] = None
NoncurrentVersionTransition: Optional[NoncurrentVersionTransition] = None
ExpirationDate: Optional[str] = None
ExpirationInDays: Optional[int] = None
Transition: Optional[Transition] = None
Id: Optional[str] = None
AbortIncompleteMultipartUpload: Optional[AbortIncompleteMultipartUpload] = None

class WebsiteConfiguration(BaseModel):
RoutingRules: Optional[List[RoutingRule]] = None
IndexDocument: Optional[str] = None
RedirectAllRequestsTo: Optional[RedirectAllRequestsTo] = None
ErrorDocument: Optional[str] = None

class TopicConfiguration(BaseModel):
Event: str
Topic: str
Filter: Optional[NotificationFilter] = None

class IntelligentTieringConfiguration(BaseModel):
Status: str
TagFilters: Optional[List[TagFilter]] = None
Tierings: List[Tiering]
Id: str
Prefix: Optional[str] = None

class StorageClassAnalysis(BaseModel):
DataExport: Optional[DataExport] = None

class LambdaConfiguration(BaseModel):
Function: str
Event: str
Filter: Optional[NotificationFilter] = None

class ReplicationRuleFilter(BaseModel):
Prefix: Optional[str] = None
And: Optional[ReplicationRuleAndOperator] = None
TagFilter: Optional[TagFilter] = None

class BucketEncryption(BaseModel):
ServerSideEncryptionConfiguration: List[ServerSideEncryptionRule]

class LifecycleConfiguration(BaseModel):
Rules: List[Rule]

class QueueConfiguration(BaseModel):
Event: str
Filter: Optional[NotificationFilter] = None
Queue: str

class ReplicationRule(BaseModel):
Status: str
Destination: ReplicationDestination
Filter: Optional[ReplicationRuleFilter] = None
Priority: Optional[int] = None
SourceSelectionCriteria: Optional[SourceSelectionCriteria] = None
Id: Optional[str] = None
Prefix: Optional[str] = None
DeleteMarkerReplication: Optional[DeleteMarkerReplication] = None

class ReplicationConfiguration(BaseModel):
Role: str
Rules: List[ReplicationRule]

class AnalyticsConfiguration(BaseModel):
TagFilters: Optional[List[TagFilter]] = None
StorageClassAnalysis: StorageClassAnalysis
Id: str
Prefix: Optional[str] = None

class NotificationConfiguration(BaseModel):
QueueConfigurations: Optional[List[QueueConfiguration]] = None
LambdaConfigurations: Optional[List[LambdaConfiguration]] = None
TopicConfigurations: Optional[List[TopicConfiguration]] = None

class Model(BaseModel):
InventoryConfigurations: Optional[List[InventoryConfiguration]] = None
WebsiteConfiguration: Optional[WebsiteConfiguration] = None
DualStackDomainName: Optional[str] = None
AccessControl: Optional[str] = None
AnalyticsConfigurations: Optional[List[AnalyticsConfiguration]] = None
AccelerateConfiguration: Optional[AccelerateConfiguration] = None
PublicAccessBlockConfiguration: Optional[PublicAccessBlockConfiguration] = None
BucketName: Optional[str] = None
RegionalDomainName: Optional[str] = None
OwnershipControls: Optional[OwnershipControls] = None
ObjectLockConfiguration: Optional[ObjectLockConfiguration] = None
ObjectLockEnabled: Optional[bool] = None
LoggingConfiguration: Optional[LoggingConfiguration] = None
ReplicationConfiguration: Optional[ReplicationConfiguration] = None
Tags: Optional[List[Tag]] = None
DomainName: Optional[str] = None
BucketEncryption: Optional[BucketEncryption] = None
WebsiteURL: Optional[str] = None
NotificationConfiguration: Optional[NotificationConfiguration] = None
LifecycleConfiguration: Optional[LifecycleConfiguration] = None
VersioningConfiguration: Optional[VersioningConfiguration] = None
MetricsConfigurations: Optional[List[MetricsConfiguration]] = None
IntelligentTieringConfigurations: Optional[
List[IntelligentTieringConfiguration]
] = None
CorsConfiguration: Optional[CorsConfiguration] = None
Id: Optional[str] = None
Arn: Optional[str] = None
```