[TASK] Cache requireJS configuration

This avoids lots of filesystem I/O because it does not crawl all
extensions on each BE request anymore.

Resolves: #69172
Releases: master
Change-Id: Ibe83caed164f78f51718fbd34e334f980a8e40d8
Reviewed-on: https://review.typo3.org/42730


Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Stephan Großberndt <stephan@grossberndt.de>
Tested-by: Stephan Großberndt <stephan@grossberndt.de>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>