[red-knot] Add `typing.Any` as a spelling for the Any type (#14742)
We already had a representation for the Any type, which we would use
e.g. for expressions without type annotations. We now recognize
`typing.Any` as a way to refer to this type explicitly. Like other
special forms, this is tracked correctly through aliasing, and isn't
confused with local definitions that happen to have the same name.
Closes #14544