Mypy incorrectly infers that parameters are positional-only for `__eq__` methods autogenerated with `@dataclass`

For a class decorated with @dataclass, mypy assumes that the class's __eq__ method will have the exact same signature as object.__eq__. However, this is subtly incorrect. Whereas the signature of object.__eq__ is def __eq__(self, other: object, /) -> bool: ..., the signature of MyDataclass.__eq__ is def __eq__(self, other: object) -> bool: .... I.e., for the method auto-generated by @dataclass, the second argument is positional-or-keyword; whereas the second argument is positional-only for object.__eq__.

Minimal repro (using mypy 0.931, Python 3.10 -- try it on mypy playground here):

from dataclasses import dataclass

@dataclass
class Foo: ...

reveal_type(Foo.__eq__)  # Revealed type is "def (builtins.object, builtins.object) -> builtins.bool"

Start with the minimal dataclass reproduction and inspect how mypy handles the autogenerated eq method compared with object.eq. Verify the revealed signature, then add coverage showing that the second parameter is positional-or-keyword for dataclass equality methods; done means the incorrect positional-only inference is gone.