Allow editors to know that undo is unsupported

This avoids confusing behaviour
Introduce M.query to allow easy lookup of query string parameters
Use a nasty alert since this is an edge case and won't be surfaced
to too many people thus doesn't really warrant much new design work
(Note a toast might be missed)

Bug: 54851
Change-Id: If3b681e0de598dca32719fa0f71a7653aaa0bf77
Merge "Allow editors to know that undo is unsupported"