Rotated boxes support for GPU GenerateProposals op (#15470)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15470
On top of D13509114 and D13017791. Pretty straight-forward.
Reviewed By: newstzpz
Differential Revision: D13536671
fbshipit-source-id: ff65981b70c63773ccc9aef3ff28e3c9508f6716
