Port /test/cpp_extensions/rng_extension.cpp to new operator registration API (#39459)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/39459
Update to this PR: this code isn't going to fully solve https://github.com/pytorch/pytorch/issues/37010. The changes required for 37010 is more than this PR initially planned. Instead, this PR switches op registration of rng related tests to use the new API (similar to what was done in #36925)
Test Plan:
1) unit tests
Imported from OSS
Reviewed By: ezyang
Differential Revision: D22264889
fbshipit-source-id: 82488ac6e3b762a756818434e22c2a0f9cb9dd47
