Added OpInfo for addmm (#55920)
Summary:
Added an OpInfo for `addmm` & ported its `method_tests`
Skipping `test_variant_consistency_eager` on CPU, as it's blocked by https://github.com/pytorch/pytorch/issues/56233
Pull Request resolved: https://github.com/pytorch/pytorch/pull/55920
Reviewed By: agolynski
Differential Revision: D27800325
Pulled By: heitorschueroff
fbshipit-source-id: 311cd26c6b491b486f652cf64275c6901fea03c5
