Update test for equivalency to include region binders in object types, add new tests relating to HRTB, consolidate the `unboxed_closures` and `overloaded_calls` feature gates.
Update test for equivalency to include region binders in object types, add new tests relating to HRTB, consolidate the `unboxed_closures` and `overloaded_calls` feature gates.

rust-lang/reference,rust-lang/reference