Simplify stubs management without types.requirements()

[brandonchinn178]

Fixes #86

The current implementation has a few limitations:

• Naive parser for requirements.txt
  • Fails with extras, like types-boto3[all]
• No obvious way to specify types stubs whose name doesn't match (e.g. grpc-stubs <-> grpcio)
• No obvious way to specify local stubs
  • How to add stubs #86

This PR makes the following changes:

1. Remove py_type_library altogether and put the types libraries in PYTHONPATH instead of MYPYPATH
   • AFAICT the only reason for py_type_library is to remove the -stubs suffix because MYPYPATH requires the name to be exact. But mypy already has logic to ignore the -stubs suffix if it's on PYTHONPATH ("installed in the current Python environment"), so we should just use that
2. Remove types.requirements() in MODULE.bazel with load_stubs() helper in aspects.bzl
   • load_stubs() takes in the all_requirements output from @pip//:requirements.bzl, which contains the requirements that rules_python already parsed
   • load_stubs() makes it clear that requirements is just an automatic detection, but there's also an overrides mechanism for manually specifying the mapping (i.e. requirements is just a shortcut for manually specifying overrides for everything)

[brandonchinn178]

Not sure why CI is failing:
https://github.com/theoremlp/rules_mypy/actions/runs/15222881838/job/43979289207

Inputs 'owner' and 'repositories' are not set. Creating token for this repository (theoremlp/rules_mypy).
Error: [@octokit/auth-app] appId option is required

[brandonchinn178]

@apalmer-theorem Thoughts on this PR?

[markelliot]

Sorry for the delay here, aiming to review in the next week or so.

[michael-pplx]

I think it would be helpful if an override value could be a list of stubs. For some reason aiobotocore has several stub packages:

• types-aiobotocore which has several extras, e.g. types-aiobotocore[dynamodb,s3,sqs]
• and also individual packages:
  • types-aiobotocore-dynamodb
  • types-aiobotocore-s3
  • types-aiobotocore-sqs
  • etc.

I believe since rules_mypy doesn't understand extras, one would need to be able to specify something like:

    overrides = {
        requirement("aiobotocore"): [
            requirement("types_aiobotocore_dynamodb"),
            requirement("types_aiobotocore_s3"),
            requirement("types_aiobotocore_sqs"),
        ],
    },

[michael-pplx]

It seems that type packages don't get included transitively.
Given

- a/
  - BUILD
  - __init__.py
- b/
  - BUILD
  - __init__.py 

where

# a/__init__.py
from types_aiobotocore_dynamodb.type_defs import (
    TableAttributeValueTypeDef,
)

# b/__init__.py
from a import TableAttributeValueTypeDef
reveal_type(TableAttributeValueTypeDef)  # Any