Support invoking other classmethods within classmethods whose cls param is annotated to be type[T]

[grievejia]

Minimal repro:

class Foo:
    @classmethod
    def foo[T: Foo](cls: type[T]) -> None:
        cls.bar()
    
    @classmethod
    def bar(cls) -> None:
        pass

Expected: No error
Actual: Object of class TypeVar has no attribute bar [missing-attribute]