Add a script to delete manual user global.js/css pages

On Wikimedia wikis, users have created local common.js/css
pages that load their "global.js/css" pages from Meta-Wiki.
This script will check if those pages match a conservative
regex, and only have one revision. If so, it deletes them.

Bug: 68933
Change-Id: I4b3218ccbbc7754a89846f5fec4d288d86ed46bf
(cherry picked from commit dbdcceb182da5efbc3fe4013c26503ea721d4ea1)