improve members_from_class (register constructor dep)
Summary:
- this diff set out with the intent of registering the dependency of a class on its parent constructor and achieves that i think
- along the way i appear to have discovered missing logic for applying substitutions for type & class constants in `members_from_class` (most of) which i filled in (and left a TODO on a bit more)
- the return type of `DependencyRegistrar::add_dependency` induced a need to make many of the functions in `inherit.rs` which did compute `()` now compute `Result<()>` (which though unexpected is i guess is a good thing)
Differential Revision:
D35050144
fbshipit-source-id:
69e00ec38bf8fabb3357f5f0438f3b4fc6909722