[llvm] [Github] Add ability to filter jobs in job counting script (PR #82136)

[Tom Stellard via llvm-commits]

tstellar wrote:

> This also depends on [PyGithub/PyGithub#2902](https://github.com/PyGithub/PyGithub/pull/2902) (and probably them tagging a new release as well). Not sure exactly when that will happen.

Will the script still work with older versions of pygithub if you don't use this new option?

https://github.com/llvm/llvm-project/pull/82136