Check class references to catch non-existant classes in match cases

[A5rocks]

Fixes #20018.

[hauntsaninja]

Nice, thanks!

[A5rocks]

For the primer, (since I was confused about this for test results) this happens because there's no type annotations in the function signature so everything becomes Any, leading to Too many positional patterns for class pattern. Maybe I should remove that error for Any?

[hauntsaninja]

Maybe see if using type_info_from_type helps

[A5rocks]

The issue was moreso that we didn't get __match_args__ for AnyType... but now hopefully the behavior is nicer. (This is an improvement over before, too!)

[github-actions]

Diff from mypy_primer, showing the effect of this PR on open source code:

ibis (https://github.com/ibis-project/ibis)
- ibis/common/tests/test_grounds_py310.py:38: error: Too many positional patterns for class pattern  [misc]