fix: prevent redundant tags being added to AWS::ApiGatewayV2::Api

[gracelu0]

Issue #, if available

Currently if a user sets PropagateTags to True in the "AWS::Serverless::HttpApi" resource and specifies the DefinitionBody property with an OpenApi definition, they will encounter the following deploy-time error:

Redundant fields [tags={"TagKey":"TagValue","httpapi:createdBy":"SAM"}] provided when either Body or BodyS3Location is not empty

CloudFormation does not allow both the Tags property being set and x-amazon-apigateway-tag-value being set in the Body property.

Description of changes

Update assign_tags() method for ApiGatewayV2HttpApi class to return (no-op).

For context, Tags can only be defined when DefinitionBody is specified or else we raise an error. Also, DefinitionBody (OpenApi definition) will always be defined because we have a plugin that generates a skeleton OpenApi definition before the transform if the user does not define one. Additionally Tags always gets added to the DefinitionBody (see x-amazon-apigateway-tag-value property).

For AWS::ApiGatewayV2::Api resource, CloudFormation does not allow Tags to be defined if the Body property is specified. SAM ensures Body will always be defined. Therefore no need to add Tags property (doing so will only cause the error specified above).

Description of how you validated changes

Added transform tests and updated existing transform tests which would fail on deployment currently. Ran make test and all tests pass.

Also reproduced error and deploying the updated template succeeds without errors

Checklist

• [x] Adheres to the development guidelines
• [x] Add/update transform tests
  • [ ] Using correct values
  • [ ] Using wrong values
• [ ] Add/update integration tests

Examples?

Please reach out in the comments if you want to add an example. Examples will be added to sam init through aws/aws-sam-cli-app-templates.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.