[TASK] Improve usability by adding filters to TCA fields

To improve the usability of the backend, filters should be provided where it makes
sense, especially where it is likely to have more records.

- FE Groups: Subgroup selection
- FE User: Group selection
- BE User: Group selection

Resolves: #66621
Releases: master
Change-Id: I483c22487f89f79f313bd72e0bb6fce49efab3fa
Reviewed-on: http://review.typo3.org/38982


Reviewed-by: Andreas Fernandez <andreas.fernandez@aspedia.de>
Tested-by: Andreas Fernandez <andreas.fernandez@aspedia.de>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>