[BUGFIX] Respect lowercase „as“ in quoteIdentifiersForSelect

QueryBuilder->quoteIdentifiersForSelect() now supports lowercase
and mixedcase „as“ to detect alias names for fields.

Resolves: #81946
Releases: master, 8.7
Change-Id: Ib79088e3dd677efd24674d7aa9f5c3f4c973ec8d
Reviewed-on: https://review.typo3.org/53575


Reviewed-by: Jan Helke <typo3@helke.de>
Tested-by: Jan Helke <typo3@helke.de>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>