`Any` subclass in `Dict` not being compatible with `Any` generates confusing message

Found by @nipunn1313 in python/typeshed#4237. Please consider:

from typing import Any, Dict

class Foo(Any):
    pass

d: Dict[Foo, Foo]

def bar(x: Dict[str, str]) -> None:
    pass

bar(d)  # error: Argument 1 to "bar" has incompatible type "Dict[Foo, Foo]"; expected "Dict[str, str]"

This fails with the error marked inline, while this passes:

from typing import Any, Dict

class Foo(Any):
    pass

foo: Foo

def bar(x: str) -> None:
    pass

bar(foo)

mypy version 0.780, Python 3.8.2.

Start by running the supplied Python reproducer with mypy and compare its diagnostics for Dict[Foo, Foo] and Foo, using the reported mypy 0.780 behavior as the baseline. Trace the type-compatibility path for a Dict containing a subclass of Any. Done means the Dict case no longer produces the confusing incompatible-type message while the scalar Any-subclass case remains valid.