chgrp owner not in group

[will-moore]

Error reported at https://www.openmicroscopy.org/qa2/qa/feedback/29521/

We previously assumed that the owner of the data we're chgrp-ing is a member of the
group that the data starts in. But this may not be true (see workflow described on QA link).

To test:

• Choose some data (P/D/I etc) that you want to move to a new user and group, where the user is not a member of the starting group.
• Use $ omero chown username Dataset:1 to change the ownership
• Login to webclient as an Admin, browse to the group showing data from "All Members"
• Select the object(s) - see that the ownership has been switched to the target user (that isn't a member of the current group)
• Choose chgrp...
• You should see a list of the groups that the data owner is a member of (this failed before)
• choose one, and move the data to that group as normal.

[mtbc]

Ah yes, the "All Members" trick is useful. 👍