[BUGFIX] Re-implement GFX[thumbnails] for Backend

The option to disable thumbnails globally for every
backend user in various places does not work anymore,
but is still quite useful. The patch re-introduces the option
to not show the thumbnail in various places.

Resolves: #60497
Releases: master
Change-Id: I28e8bf86563032df8008c7de9aa7861bb5c0e2c0
Reviewed-on: https://review.typo3.org/45138


Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Daniel Goerz <ervaude@gmail.com>
Tested-by: Daniel Goerz <ervaude@gmail.com>
Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Reviewed-by: Morton Jonuschat <m.jonuschat@mojocode.de>
Tested-by: Morton Jonuschat <m.jonuschat@mojocode.de>