allow for pulling/integration of custom roles, policies

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

_No response_

### Is this related to another service?

lambda

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

I created a pre-signup cognito lambda, to check against, and prevent duplicate emails, via the aws web interface.

I then had to create a policy to allow for the cognito ListUsers permission. I then had to edit my pre-signup cognito lambda's role, to add the policy I had just created (for cognito ListUsers).

At this point, ideally, I would have preferred to do something like 'amplify pull --appId xxxxxxx --envName dev' and have amplify detect that I had added the lambda, and be able to pull it into my current amplify project, along with the role and policy I created.

I think if you set up a dependency graph, amplify should be able to traverse the dependency graph and pull in custom lambdas, policies, roles, if they are part of the dependency graph.

As it is now, I ended up having to re-add a brand new lambda via 'amplify add function', and then I had to go the aws console and re-establish the pre-signup cognito link, and re-associate the aforementioned cognito ListUsers policy to this new lambda.

And, I have NO idea how to integrate the aws console changes so that it will work with Amplify going forwards. At this point, I think I would have manually go into the aws console, and manually check/fix the manual settings I had configured (create new permission policy, associate lambda with cognito pre-signup, add newly created permission policy with the lambda's current role), if I wanted to deploy to a different environment, such as prod.

### Describe the solution you'd like

At this point, ideally, I would have preferred to do something like 'amplify pull --appId xxxxxxx --envName dev' and have amplify detect that I had added the lambda, and be able to pull it into my current amplify project, along with the role and policy I created.

### Describe alternatives you've considered

manually adding policies, lambdas, roles via the aws console, and keeping notes so that I can do the same later on in a
different environment, such as prod.

### Additional context

_No response_

### 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