(amplify-alpha): Add support for CodeStarSourceCodeProvider similar to CodePipeline's

### Describe the feature

https://docs.aws.amazon.com/amplify/latest/userguide/setting-up-GitHub-access.html#setting-up-github-app-cloudformation

> Existing Amplify apps that you previously connected from GitHub repositories use OAuth for repo access. This can include apps that you deployed using the Amplify Command Line Interface (CLI), AWS CloudFormation, or the SDKs. We strongly recommend that you migrate these apps to use the new Amplify GitHub App. Migration must be performed in the Amplify console in the AWS Management Console. For instructions, see [Migrating an existing OAuth app to the Amplify GitHub App](https://docs.aws.amazon.com/amplify/latest/userguide/setting-up-GitHub-access.html#migrating-to-github-app-auth).

As stated above, there is no method to build Amplify using GitHub App. I hope for the support of CodeStarSourceCodeProvider similar to `aws-cdk-lib/aws-codepipeline-actions`.

https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_codepipeline_actions.CodeStarConnectionsSourceAction.html

### Use Case

Migrating an existing OAuth app to the Amplify GitHub App.

### Proposed Solution

```typescript
const amplifyApp = new amplify.App(this, 'Amplify', {
appName: 'app',
buildSpec: { ... },
sourceCodeProvider: new amplify.CodeStarSourceCodeProvider({
owner: 'owner',
repository: 'repo',
connectionArn: 'arn string'
}),
});
```

### Other Information

_No response_

### Acknowledgements

- [ ] I may be able to implement this feature request
- [ ] This feature might incur a breaking change

### CDK version used

aws-cdk-lib: 2.142.1, @aws-cdk/aws-amplify-alpha: 2.149.0-alpha.0

### Environment details (OS name and version, etc.)

macOS 14.2

Start with the amplify-alpha App and its sourceCodeProvider option, then compare the requested provider with aws-cdk-lib/aws-codepipeline-actions and CodeStarConnectionsSourceAction. The work is done when an Amplify app can use a connectionArn with owner and repository for GitHub App access, with coverage in the relevant Amplify tests.

Written by the indexing model from the issue text.