Add support for log_softmax (#47409)
Summary:
This diff adds support for `log_softmax` op in NNC.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/47409
Reviewed By: ejguan
Differential Revision: D24750203
Pulled By: navahgar
fbshipit-source-id: c4dacc7f62f9df65ae467f0d578ea03d3698273d
