[functorch] Ported `view` op to the new API (pytorch/functorch#137)
* Ported `view` op to the new API
Description:
- Ported `view` op to the new API
- Updated test_view
* Refactored same code into local getPhysicalShape
* WIP removed registrations for reshape_as and view_as
* WIP Fix getPhysicalShape and segfault with unsqueeze
* Fixed view/reshape br implementations
