MDLSITE-2635: list the changed files between 2 commits
MDLSITE-2635: Decide if the job can be skipped

This script looks for the changes between 2 commits
and matches the changed files against an array of rules.

If there is any match, then the job cannot be skipped (exit
status = 0). If there isn't any match, then it's
safe to skip the tests (exit status = 1).