[SR] Eliminate extra permutes around softmax calls (#76391)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/76391
I've seen this pattern in many important internal models:
```
x = torch.permute(a, [0, 2, 1])
y = torch.softmax(x, 2)
z = torch.permute(y, [0, 2, 1])
```
This is equivalent to
```
z = torch.softmax(x, 1)
```
The `permute` ops can degrade performance, especially if copy variants are on. Add another pattern to our `EliminateExtraPermuteOpsPass` to handle this.
ghstack-source-id: 155466506
Test Plan: New unit tests
Reviewed By: navahgar, huiguoo
Differential Revision: D35938289
fbshipit-source-id: 398b5528077b0b3f1c6fc5544e483803e96d68e9
(cherry picked from commit d742abd094d1fef23ca6a34703d97a6da2d14bd1)
