Lightweight String check Utility (#16858)
Summary:
light weight implementation of LLVM filecheck utility. Currently only handles string matching - regexes & saving a regex to a variable name can be added as needed.
Current intended usage is through FileCheckBuilder python handle, and is shown in the tests.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/16858
Differential Revision: D14096244
Pulled By: eellison
fbshipit-source-id: c7c8d1457691c105e6ccbb3c1a378d96baac2569
