[FEATURE] Allow calling toArray() on ObjectStorage using name getArray()

This change adds an alias method which allows ObjectStorage's
values to be accessed using a "get"-prefixed method name which
in turn allows the values to be addressed using numerical
indices or converted to arrays on-the-fly by adding an ".array"
segment to the property path.

Change-Id: Ibe94910d6043a52c7ef330e18e0330021ecbb325
Resolves: #73752
Releases: master
Reviewed-on: https://review.typo3.org/46961


Reviewed-by: Oliver Hader <oliver.hader@typo3.org>
Tested-by: Oliver Hader <oliver.hader@typo3.org>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>