Implement rotated generate_proposals_op without opencv dependency (1.8x faster) (#18010)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/18010
[C2] Implement rotated generate_proposals_op without opencv dependency.
Reviewed By: newstzpz
Differential Revision: D14446895
fbshipit-source-id: 847f2443e645f8cae1327dfbaa111c48875ca9be
