Support stack-level tags for `AWS::Amplify::App` resource type

### Name of the resource

AWS::Amplify::App

### Resource name

_No response_

### Description

Stack-level tags are not propagated to the `AWS::Amplify::App` resource type, despite supporting the `Tags` property.

### Other Details

https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-amplify-app.html

Start by reading the AWS::Amplify::App CloudFormation resource documentation linked in the issue and locate the repository's handling for stack-level tag propagation. Confirm the existing Tags property behavior, then verify that stack-level tags are propagated to AWS::Amplify::App and add coverage for the resource type; done means the relevant tests pass.

Written by the indexing model from the issue text.