[red-knot] Subclasses of Any should be assignable to `Callable`

Subclasses of `Any` should be assignable to `Callable`. This should not be an error:

```py
from typing import Callable, Any


class MyMock(Any):
    pass

def f(c: Callable):
    c()

f(MyMock())  # Argument to this function is incorrect: Expected `(...) -> Unknown`, found `MyMock`
```
(https://types.ruff.rs/e0ded89d-526c-430e-a9c5-d02b8945f81d)