CLI download looks for resources in all user groups (fix #12146).

This PR updates the logic used by ``bin\omero download``. Now all groups in which the logged in user is present are used when looking for an Image / OriginalFile / FileAnnotation ID. To test, follow scenario from http://trac.openmicroscopy.org.uk/ome/ticket/12146. Try out downloading an Image, FileAnnotation and OriginalFile.

\cc @joshmoore, @sbesson: I'd appreciate feedback with regards to code and test structure - happy to correct if there is too much copypasta.