Split out RegisterDispatchKey to its own file (#51508)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/51508
No substantive changes. The codegen for this file was getting a
bit long so I moved it off into tools.codegen.dest submodule (I
wanted to do tools.codegen.gen but that conflicts with the existing
module; oy vey!) To do this I had to move some other functions around
so that they were more generally accessible. Otherwise
self-explanatory.
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
Test Plan: Imported from OSS
Reviewed By: ljk53
Differential Revision: D26187856
Pulled By: ezyang
fbshipit-source-id: fd3784571d03d01c4acb7ca589fcde4492526408
