[BUGFIX] Streamline queue objects on dependency check

The data stored in different download queues mixes arrays and objects.
Therefore you cannot loop over all queues and call functions of extension
objects. This patch streamlines all objects and make sure always objects
are returned.

Releases: master, 6.2
Resolves: #66798
Change-Id: I6eedefb614145b8645c7c52ff5daa7ad6c9c38e7
Reviewed-on: http://review.typo3.org/39276


Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Helmut Hummel <helmut.hummel@typo3.org>
Tested-by: Helmut Hummel <helmut.hummel@typo3.org>
Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Tested-by: Andreas Fernandez <typo3@scripting-base.de>