Putting the dropdown content in the details elemenet have been inconsistent.
Transition are not working correctly and different browsers are not handling it well.
Furthermore, the previous implementation does not allow an always visible state of dropdown content.
Fixes: #882
This will allow the search suggestion to hook up to multiple search
boxes with `.citizen-search-box` as container. Do note that the default
Citizen suggestion is hardcoded for the primary search, so it only
works for the old core search suggestion module.
This is also a prereq for implementing the Codex search like the one
from Vector.
Mostly based on Vector 2022. Now we target checkbox hacks by the HTML classes
.mw-checkbox-hack-TYPE instead of defining each individually, which would
make it more scalable.
