[special] Alias for special.expm1 and special.exp2 (#54670)
Summary:
Reference: https://github.com/pytorch/pytorch/issues/50345
Pull Request resolved: https://github.com/pytorch/pytorch/pull/54670
Reviewed By: H-Huang
Differential Revision: D27401440
Pulled By: mruberry
fbshipit-source-id: 02b1fd0e8ffd3f5a017d6b6b9229b76b92b4b745
