[TASK] Add prepended icon to SelectSingleElement

This brings back the select prepend icon and moves all event
handling for updating it to a RequireJS module.

Also moves all remaining event handling to the module including
FormEngine "fieldChangeFunc" and "onFocus".

Resolves: #69792
Releases: master
Change-Id: I9943412bb61639759aeba05746facdce60cfd12e
Reviewed-on: http://review.typo3.org/43306


Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Michael Oehlhof <typo3@oehlhof.de>
Tested-by: Michael Oehlhof <typo3@oehlhof.de>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>