[BUGFIX] Create proper array of cached icons

Change the handling of fetching cached icons to create a proper
array containing only one object instead of having an object
per icon.

Resolves: #70730
Related: #70583
Releases: master
Change-Id: I863504bf4178367551849fbc5e82541a252318f7
Reviewed-on: http://review.typo3.org/44069


Reviewed-by: Frank Nägler <frank.naegler@typo3.org>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Mathias Brodala <mbrodala@pagemachine.de>
Reviewed-by: Morton Jonuschat <m.jonuschat@mojocode.de>
Tested-by: Morton Jonuschat <m.jonuschat@mojocode.de>