AWS::ECR::Repository - support tagging

1. Title -> AWS::ECR::Repository - support tagging
2. Scope of request -> Support tagging for an ECR Repository
3. Expected behavior -> when a tag gets added to any ECR Repository, add that tag to the provisioned resource as well
4. Test case recommendation (optional) -> 
5. Links to existing API doc (optional) -> 
6. Category tag (optional) -> Compute
7. Any additional context (optional) -> 