allow building Lambda Layers with npm scripts `amplify:<layer-name>`

### Amplify CLI Version

12.8.2

### Question

I just read about the ability of the amplify cli to call all scripts in the root directory that start with `amplify:` on `amplify push -y`. But it doesn't seem to work. Is this still a feature?

The issue names no files, tests, or entry points. Start by reproducing the reported behavior with a root npm script named amplify: and amplify push -y; done means determining whether the script is supported and, if not, identifying the CLI behavior that needs correction or clarification.

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