Implemented types are obscured by intermediate private types

[jcollins-g]

Similar to #1623, implemented types only show directly implemented types and don't currently take into account that indirectly implemented types may not be exposed.

from @natebosch:

Another place I notices is that Queue doesn't show it implements Iterable because of the not-exposed EfficientLengthIterable class, but shows all the iterable methods as inherited.

Originally posted by @natebosch in #1623 (comment)

[jcollins-g]

#2495 fixes most of this, however type parameters are not properly converted across.

[srawlins]

Forking that last bug into a new issue. #2997