Expose certain methods in OpaqueTensorImpl. (#41060)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/41060
Exposes a const ref opaque_handle and made copy_tensor_metdata a
protected method. This helps in reusing code in sub classes of OpaqueTensorImpl
Test Plan: waitforbuildbot
Reviewed By: dzhulgakov
Differential Revision: D22406602
fbshipit-source-id: e3b8338099f257da7f6bbff679f1fdb71e5f335a
