Add hook to sync repo to staging repository

Summary:
Add secondary commit hook for staging repos

very simple logic, is user scmupdate? allow everything, else just
phabricator tags creation

Also don't send out the any notifications at all.

Add phab arcconfig

Test Plan: none so far

Reviewers: bcooksley

Maniphest Tasks: T9037

Differential Revision: https://phabricator.kde.org/D13759