Add a runtime cache for icons and remove the calls to getDeprecationSettings.

Resolves: #73606
Releases: master
Change-Id: I28fe3721db105cbd41c8beb45afc36903e3f945f
Reviewed-on: https://review.typo3.org/46808


Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>