Clearly show in the Amplify console if an "amplify.yml" file is overriding the build settings

### Before opening, please confirm:

- [X] I have checked to see if my question is addressed in the [FAQ](https://github.com/aws-amplify/amplify-hosting/blob/master/FAQ.md).
- [X] I have [searched for duplicate or closed issues](https://github.com/aws-amplify/amplify-hosting/issues?q=is%3Aissue+).
- [X] I have read the guide for [submitting questions](https://github.com/aws-amplify/amplify-hosting/blob/master/CONTRIBUTING.md).
- [X] I have removed any sensitive information from my code snippets and submission.

### App Id

NEW_APP

### AWS Region

us-east-1

### Amplify Hosting feature

Build settings

### Is your feature request related to a problem? Please describe:

In the Amplify console, under Build settings, it states:

`To modify your app's build spec choose 'Edit'. Alternatively, you may download the YML file and deploy in the root of your repository to as amplify.yml to override this setting.`.

I downloaded the file and created it at the root of my repository.

However, the Build settings screen doesn't indicate that I've overridden the settings with the amplify.yml file.

### Describe how you'd like this feature to work

It would be nice if there were an indication on the Build settings screen that an amplify.yml file is present in the repository that is overriding the settings.

Start with the Amplify console's Build settings screen and the repository-root amplify.yml workflow described in the issue. Trace how the console determines or displays build settings, then identify how the presence of an overriding amplify.yml could be surfaced; done means the screen clearly indicates when repository settings override console settings.

Written by the indexing model from the issue text.