[TASK] Show remaining characters in BE user settings module

The fields name & email are saved in the database and therefore
the length of its value should be checked client side to give users
a hint about the maximal length.

Use the requireJS module of FormEngine for providing the
information about the remaining available characters.

Resolves: #79532
Releases: master, 7.6
Change-Id: Ic727fcae493060fed45ddf5b3d05c5070b236a0f
Reviewed-on: https://review.typo3.org/51458


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>
Tested-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>
Reviewed-by: Susanne Moog <susanne.moog@typo3.org>
Tested-by: Susanne Moog <susanne.moog@typo3.org>