Add filter to run workflow tests only when needed

Add filter to CI workflows to run tests only on the code tested that is actually changed on a PR. When a GHA workflow is changed, torchcodec-xpu tests for instance shouldn't run unless the change impact them. Example given: torchcodec-xpu tests should run if there are changes in Python versions to try, but they shouldn't if the workflow changed is OpenSSF scorecard or Coverity.