Resource-based policy permissions are exceeded when many log group triggers are provided

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## Describe the Bug
When supplying a large number of keys (>50) to `cloudwatch_forwarder_log_groups`, resource-based policy permissions throws a `PolicyLengthExceededException` with no way to recover. In addition to this, when the exception is thrown by the AWS SDK, terraform does not stop attempting to run `PutSubscriptionFilter` for every log group provided, with up to 25 retries each. This leads to incredibly long `terraform apply` times without any apparent reason if you don't have `TF_LOGS` set.

## Expected Behavior
Provide any number of `cloudwatch_forwarder_log_groups` to the module that scales.

## Potential fix?
Allow user to supply a "catch-all" source arn that can provide permissions to a larger number of log groups.

## Steps to Reproduce
Steps to reproduce the behavior:
1. Add new `datasource` referencing your account log groups.
```
data "aws_cloudwatch_log_groups" "user_log_groups" {
log_group_name_prefix = "/aws/lambda/${var.resource_prefix}"
}
```
2. Map `datasource` to local variable
```
locals {
log_groups = { for value in data.aws_cloudwatch_log_groups.user_log_groups.log_group_names :
# Remove invalid key characters
trim(replace("${value}", "/", "-"), "-") => {
name = "${value}"
filter_pattern = ""
}
}
}
```
3. Provide to `cloudposse/datadog-lambda-forwarder/aws` module
```
cloudwatch_forwarder_log_groups = local.log_groups
```
4. Run `terraform apply` with `TF_LOGS` set to DEBUG to see SDK calls `lambda/AddPermission` and `logs/PutSubscriptionFilter` failing

## Screenshots
If applicable, add screenshots or logs to help explain your problem.
```
module.DataDogIntegration.module.datadog_lambda_forwarder.aws_lambda_permission.cloudwatch_groups[REDACTED]: Creating...
2022-09-12T14:23:19.719+0800 [INFO] provider.terraform-provider-aws_v3.75.2_x5: 2022/09/12 14:23:19 [DEBUG] [aws-sdk-go] DEBUG: Response lambda/AddPermission Details:
---[ RESPONSE ]--------------------------------------
HTTP/2.0 400 Bad Request
Content-Length: 91
Content-Type: application/json
Date: Mon, 12 Sep 2022 06:23:19 GMT
X-Amzn-Errortype: PolicyLengthExceededException
X-Amzn-Requestid: 5e0ad4a0-f35d-4314-8601-fb2c48d7be13

-----------------------------------------------------: timestamp=2022-09-12T14:23:19.719+0800
2022-09-12T14:23:19.719+0800 [INFO] provider.terraform-provider-aws_v3.75.2_x5: 2022/09/12 14:23:19 [DEBUG] [aws-sdk-go] {"Type":"User","message":"The final policy size (20898) is bigger than the limit (20480)."}: timestamp=2022-09-12T14:23:19.719+0800
2022-09-12T14:23:19.719+0800 [INFO] provider.terraform-provider-aws_v3.75.2_x5: 2022/09/12 14:23:19 [DEBUG] [aws-sdk-go] DEBUG: Validate Response lambda/AddPermission failed, attempt 0/25, error PolicyLengthExceededException: The final policy size (20898) is bigger than the limit (20480).
{
RespMetadata: {
StatusCode: 400,
RequestID: "5e0ad4a0-f35d-4314-8601-fb2c48d7be13"
},
Message_: "The final policy size (20898) is bigger than the limit (20480).",
Type: "User"
}: timestamp=2022-09-12T14:23:19.719+0800
```

## Environment (please complete the following information):

Anything that will help us triage the bug will help. Here are some ideas:
```
terraform -v

Terraform v1.2.6
on darwin_arm64
+ provider registry.terraform.io/franckverrot/stripe v1.9.0
+ provider registry.terraform.io/hashicorp/archive v2.2.0
+ provider registry.terraform.io/hashicorp/aws v3.75.2
+ provider registry.terraform.io/hashicorp/external v2.2.2
+ provider registry.terraform.io/hashicorp/local v2.2.3
+ provider registry.terraform.io/hashicorp/random v3.4.3
+ provider registry.terraform.io/hashicorp/template v2.2.0
```

## Additional Context
[https://github.com/cloudposse/terraform-aws-datadog-lambda-forwarder/blob/373367a1338ac20706ef95c04a7ce173ebcc70e3/lambda-log.tf#L195-L203](https://github.com/cloudposse/terraform-aws-datadog-lambda-forwarder/blob/373367a1338ac20706ef95c04a7ce173ebcc70e3/lambda-log.tf#L195-L203)