ns for fx: move pattern utils to separate file (#55805)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/55805
No logic change, just moving util functions to separate file.
Test Plan:
```
python test/test_quantization.py TestFXGraphMatcher
python test/test_quantization.py TestFXNumericSuiteCoreAPIs
```
Imported from OSS
Reviewed By: jerryzh168
Differential Revision: D27719982
fbshipit-source-id: c80d5397c1efeb9fc83eacaa532ecbde557cca3f
