XWIKI-11124: Flamingo badly extending .checkbox class for input[type='checkbox'] elements

(cherry picked from commit e53da425931c105d587ca3bb9ea8d4c0477f3db9)
XWIKI-10920: Document checkboxes aren't fully visible when trying to import a XAR on Flamingo

(cherry picked from commit ad681363d1f03b243be818b5b1660a0a9f895335)
XWIKI-10885: "Hidden document" is not perfectly aligned with its checkbox

(cherry picked from commit d03c0bbf2fcbef5877b8263c0d0f4fc474c967db)