ExtDirect StateProvider seems to queue Ext.state.Manager.set() calls and
collects them to fire only one AJAX call.

In TYPO3\CMS\Backend\InterfaceState\ExtDirect on the other hand setState()
only stores the first item of the data array to $GLOBALS['BE_USER']->uc
the other settings are just ignored. Instead it should iterate the data
array and store all items.

Change-Id: I8d8bd01131545a6cad1a3933184c25c6d5f26149
Fixes: #51998
Releases: 6.2, 6.1, 6.0
Reviewed-on: https://review.typo3.org/23843
Reviewed-by: Markus Klein
Tested-by: Markus Klein
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters