Orphan folder

The ```Orphaned Images``` folder displayed did not correspond to the correct group context. 
The problem was highlighted when testing the move of MIF (see https://trac.openmicroscopy.org.uk/ome/ticket/11089)

To test:
 * Log in as user-4
 * Add to the display 2 groups user-4 is a member of.
 * Expand the ```Orphaned Images``` folder for the first group.
 * Expand the ```Orphaned Images``` folder for the second group.
 * Go back to the ```Orphaned Images``` folder, The central panel should display the correct images.

This is not FS specific and will have to be rebased.