migrate export_caffe2_op_to_c10.h macros to the new dispatcher registration API (#47321)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/47321
Test Plan: Imported from OSS
Reviewed By: ezyang
Differential Revision: D24714805
Pulled By: bdhirsh
fbshipit-source-id: cd695c9c203a7fa4d5217c2466d7f274ce2cd096
