enforece dtype (#102802)
Summary: Add a flag to enforce the gather data dtype. In case backward compatibility, make the default as False
Test Plan: local and mast
Reviewed By: zyan0, strisunshinewentingwang
Differential Revision: D46295190
Pull Request resolved: https://github.com/pytorch/pytorch/pull/102802
Approved by: https://github.com/mrshenli
