Give better error messages when calling overloaded function with invalid types

[JukkaL]

Currently when calling an overloaded function, the error message is something like No overload variant of "foo" matches argument types. Instead, we should try to give a message like Argument 1 to "foo" has incompatible type "int"; expected "str" or "bytes", which is more informative. This may not be always possible, but we should be able to do it at least most of the time.

[JukkaL]

Also, if we can't give a specific message, we could print out the full signature of the target overloaded function as a note after the message. This would make it easier to see why the call is rejected by mypy.

[ilevkivskyi]

I think just listing argument types and the overloads in a note may be enough. Also protocol notes already contain relevant code for nice compact formatting of overloads.

[JukkaL]

The implementation of protocol notes lives in report_protocol_problems in mypy.messages. Overload messages are generated in no_variant_matches_arguments in the same module.

[MentalMegalodon]

I'm working on it.