LP#1839341: Really stop duplicates, and provide an initial sort order

LP#1839341: Really stop duplicates, and provide an initial sort order

Duplicates snuck back in due to something firing the getRows function
multiple times, concurrently.  We avoid this problem by returning an
empty observable if we're already mid-fetch.

This commit also sorts the settings by group and label at load time.
Finally, we bring back the "change not visible" warning when editing
for a location other than the context org as a toast.

Signed-off-by: Mike Rylander <mrylander@gmail.com>
Signed-off-by: Terran McCanna <tmccanna@georgialibraries.org>
Signed-off-by: Jane Sandberg <sandbergja@gmail.com>