Discover and check operator variants
Operator variants can now be explicitly specified in the OpInfo kwargs.
When the operator name is not the same as the method/function form this
will allow them to be discovered.
The OpInfo is extended to also accept/discover the inplace operator
variant.
Operator and inplace operator variants are exercised in consistency
tests when the sample does not contain any kwargs.
Operations which require explicit declarations of operator and inplace
operator variants have had them added to their OpInfos.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/76901
Approved by: https://github.com/mruberry
