(gen2-migration) `generate` command should handle lambda layers

### Is this feature request related to a new or existing Amplify category?

_No response_

### Is this related to another service?

_No response_

### Describe the feature you'd like to request

Lambda layers from Gen1 should be migrated to Gen2.

### Describe the solution you'd like

We should follow the Gen2 documentation and generate the recommended API.

https://docs.amplify.aws/react/build-a-backend/functions/add-lambda-layers/

### Describe alternatives you've considered

None

### Additional context

This is how lambda layers work in Gen1: https://docs.amplify.aws/gen1/javascript/build-a-backend/functions/layers/

### Is this something that you'd be interested in working on?

- [ ] 👋 I may be able to implement this feature request

### Would this feature include a breaking change?

- [ ] ⚠️ This feature might incur a breaking change