[red-knot] Add callable subtyping for callable instances and bound methods

[MatthewMckee4]

Summary

Trying to improve #17005
Partially fixes #16953

Test Plan

Update is_subtype_of.md

[github-actions]

mypy_primer results

Changes were detected when running on open source projects

rich (https://github.com/Textualize/rich)
- error[lint:invalid-argument-type] /tmp/mypy_primer/projects/rich/tests/test_progress.py:292:60: Object of type `MockClock` cannot be assigned to parameter `get_time` of function `track`; expected type `(() -> int | float) | None`
- Found 578 diagnostics
+ Found 577 diagnostics

black (https://github.com/psf/black)
- error[lint:invalid-argument-type] /tmp/mypy_primer/projects/black/src/black/__init__.py:1280:48: Object of type `<bound method `readline` of `BytesIO`> | @Todo(instance attribute on class with dynamic base)` cannot be assigned to parameter 1 (`readline`) of function `detect_encoding`; expected type `() -> bytes | bytearray`
- error[lint:invalid-argument-type] /tmp/mypy_primer/projects/black/src/black/__init__.py:1280:48: Object of type `<bound method `readline` of `BytesIO`> | @Todo(instance attribute on class with dynamic base)` cannot be assigned to parameter 1 (`readline`) of function `detect_encoding`; expected type `() -> bytes | bytearray`
- error[lint:invalid-argument-type] /tmp/mypy_primer/projects/black/src/black/__init__.py:1280:48: Object of type `<bound method `readline` of `BytesIO`> | @Todo(instance attribute on class with dynamic base)` cannot be assigned to parameter 1 (`readline`) of function `detect_encoding`; expected type `() -> bytes | bytearray`
- Found 212 diagnostics
+ Found 209 diagnostics

[MatthewMckee4]

I'm not sure this is how we will want to implement this , but i think its right to not check the name of the variable, and since staticmethod is not supported, this should be fine, but when that is implemented i think we will have to check decorators

[MichaReiser]

Not sure, but this might be a good one for @dcreager to review?

[carljm]

This looks reasonable to me! The tests are good, and we can always change the implementation of BoundMethodType::into_callable_type if we decide we need to preserve the first argument.

Thank you!