[TASK] Apply Bootstrap styling on <select> elements

Change the styling of <select> tags to get a more Bootstrap-like look&feel.
This currently works with Safari, Chrome and Firefox. Internet Explorer keeps
its native UI.

Resolves: #71395
Releases: master
Change-Id: Ifae57363d0f3ce048e581e66b27dfb862ef65ee7
Reviewed-on: https://review.typo3.org/44367


Reviewed-by: Bjoern Jacob <bjoern.jacob@tritum.de>
Tested-by: Bjoern Jacob <bjoern.jacob@tritum.de>
Reviewed-by: Frank Nägler <frank.naegler@typo3.org>
Tested-by: Frank Nägler <frank.naegler@typo3.org>