Add WaitCondition for EventBridge/SNS

### Name of the resource

AWS::CloudFormation::WaitCondition

### Resource name

_No response_

### Description

AWS has a healthy ecosystem of events bubbling away under the hood (expanding every day). However CloudFormation doesn't currently have a neat way of tapping into these events.

Please consider adding a resource which listens for them. E.g.

```
CodeBuildCompleteCondition:
Type: AWS:CloudFormation:EventBridgeCondition
EventPattern: [1]

MyLambda:
Type: AWS::Lambda::Function
Properties:
FunctionName: MyLambda
Runtime: python3.8
Handler: index.handler
Code:
S3Arn: GetAtt! CodeBuildCompleteCondition.detail.additional-information.artifact.location
```
Note: It would be useful if the output of the resource matched EB's event structure [2]. See CodeCommit example [3].

A similar mechanism could be adapted for SNS.

[1] https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-events-rule.html#cfn-events-rule-eventpattern
[2] https://docs.aws.amazon.com/eventbridge/latest/userguide/eb-events-structure.html
[3] https://docs.aws.amazon.com/codebuild/latest/userguide/sample-build-notifications.html#sample-build-notifications-ref

### Other Details

_No response_

Start with the linked EventBridge event-pattern and event-structure references, then review the CodeCommit notification example. Clarify whether the proposed CloudFormation resource should support SNS as well and define its event output; done means an agreed scope and behavior for the roadmap feature.

Written by the indexing model from the issue text.