add SequenceMask op (#60235)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/60235
This diff
- added SequenceMask op in Dper3 (caffe2 & pytorch)
- added shape inference functions for SequenceMask op
Test Plan:
```
buck test dper3/dper3/modules/low_level_modules/tests:single_operators_test -- test_sequence_mask
```
Differential Revision: D29210097
fbshipit-source-id: cab3460e0fd6c49bec6d0c5c624bd4652de7604b
