Technically, these operations belong in the ObjectiveC module, where NSObject
is defined. Keep them there. However, we need to build the mock ObjectiveC
overlay with `-disable-objc-attr-requires-foundation-module` now.
Simplify e.g., ASTContext::getBridgedToObjC(), which no longer needs
the optional return.
Eliminate the now-unused constraint kind for checking bridging to
Objective-C.
We would crash because 'Any' doesn't have a corresponding bridged type through the normal bridging mechanism. Handle this correctly, and correctly recognize 'AnyHashable' and 'Any' as the upper bounds of Dictionary, Set, and Array so we present the unqualified NS types in the generated header.
