Check for pseudo-Protocols in argument types

[srittau]

There are a few ABCs that look deceptively like protocols, but aren't, for example Sequence or Mapping. We usually have good protocol alternatives for these in typeshed, but it's easy to slip in one of these pseudo-protocols by accident. Edit: It makes sense to at least explicitly acknowledge the intentional use of these by adding a # noqa comment.

We should warn about using these in argument types, but probably as an opt-in warning (which we could eventually enable in typeshed).