Add search for filter patterns
Adds an option for searching filters with a
specific pattern in the main page, together with already existing options.
Plain search and regex are available, only for users with the
view-private right. The search is performed directly on the database.
If the user actually searched for something, it is also added a column to
Special:AbuseFilter showing a snippet of the pattern from each filter, with the query match highlighted.
Depends on: I8144062b1f273d0d8932203ffcb7a71aca60bba9