[TASK] Extend username search in beuser module

The search for a username searches now also in the columns
"uid" and "realName".

Change-Id: I8401e3c6cf73465f60a2c851dd87f28c3e0bff5c
Resolves: #72317
Releases: master, 7.6
Reviewed-on: https://review.typo3.org/45930


Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>