Resolve VCS hashes to commit URL
Summary:
Provide a small utility to find an URL representation
matching a hash, querying code review systems like Phabricator
or Gerrit, then public code hosting like GitHub or GitLab.
Test Plan: Run commands and code documented in README + make test
Reviewers: dereckson
Differential Revision: https://devcentral.nasqueron.org/D2569