Extending _get_bytecode_version to support flatbuffers format (#75021)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/75021
Extending `_get_bytecode_version` to support flatbuffers.
ghstack-source-id: 152771695
(Note: this ignores all push blocking failures!)
Test Plan:
```
~/fbsource/xplat] cd ~/fbsource/xplat/ && buck test //xplat/caffe2:test_lite_interpreter
Building: finished in 0.8 sec (100%) 327/327 jobs, 0/327 updated
Total time: 0.9 sec
Testing: finished in 06:59.5 min (85 PASS/0 FAIL)
BUILD SUCCEEDED
RESULTS FOR //xplat/caffe2:test_lite_interpreter
PASS 412.3s 85 Passed 0 Skipped 0 Failed //xplat/caffe2:test_lite_interpreter
TESTS PASSED
```
Reviewed By: iseeyuan
Differential Revision: D34900498
fbshipit-source-id: 65743076d43a933c5381ec128d0268f22c0a8441
(cherry picked from commit 457c76c7d1df6050b941c56a8198162e2e4a3388)
