Add FLOPS support to the new profiler API. (#51734)
Summary:
The new profiler API was added in PR#48280. This PR is to add FLOPS
support to the new profiler API.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/51734
Test Plan:
```python
python test/test_profiler.py -k test_flops
```
Reviewed By: xuzhao9
Differential Revision: D26261851
Pulled By: ilia-cher
fbshipit-source-id: dbeba4c197e6f51a9a8e640e8bb60ec38df87f73
