[CLEANUP] Use the Foo[] notation for arrays

This should help static code analysis and code completion.

Resolves: #63628

Change-Id: I4dce6943eb58c933e6b98479d6f1aa4ac890bc40
Reviewed-on: http://review.typo3.org/35106
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Tested-by: Oliver Klee <typo3-coding@oliverklee.de>