Treat inherited-annotated attributes as typed in pyrefly coverage

[jorenham]

Summary

A method-assigned attribute without its own annotation is no longer reported as untyped by pyrefly coverage {check, report} when a base class declares it:

class P_AttrList:
    attrs: dict[str, Any]

class DefaultStatement(P_AttrList):
    def __init__(self, attrs: dict[str, Any]) -> None:
        self.attrs = attrs  # was: untyped

It takes the type quality of the nearest base annotation, so dict[str, Any] is typed and a bare Any is any.

Fixes #3997

Test Plan

Regression tests added, and verified that check / report are still in sync

[github-actions]

According to mypy_primer, this change doesn't affect type check results on a corpus of open source code. ✅