[Static Runtime] Added logging to dump the model graphs (#65509)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/65509
With this change, we can get dumps of the model graphs by setting the env variable `PYTORCH_JIT_LOG_LEVEL=">>impl"` while running the model.
Test Plan: buck test mode/opt-clang //caffe2/benchmarks/static_runtime:static_runtime_cpptest
Reviewed By: mikeiovine
Differential Revision: D31125797
fbshipit-source-id: d8979a4e138047518140e0eaecb46e012891b17c
