[JIT] run frozen optimizations on methods other than forward (#68668)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/68668
This updates run_frozen_optimizations so that it will run on additional methods other than forward
ghstack-source-id: 143871758
Test Plan:
Added test in test_freezing.py
```
python3 test/test_jit.py -- test_conv_bn_folding_not_forward
```
Reviewed By: eellison
Differential Revision: D32567857
fbshipit-source-id: 75e56efad576404dc8d6897861d249573f5ccd7a
