- Make proxy manager use IMultiQI instead of IInternalUnknown as tests

- Make proxy manager use IMultiQI instead of IInternalUnknown as tests
  show that IInternalUnknown isn't exposed.
- Implement IMultiQI on top of IRemUnknown calls.
- Silence some fixmes that occur during tests and don't give us any
  useful information.
- Fix typo in class factory proxy that caused us to use the wrong
  offset into the CFProxy structure, causing us to not call the
  outer_unknown properly.