Moved file filtering from a toolbar spinner to a menu option.
The toolbar title is now free to display some other information.
The options are grouped, so they display radio buttons, and show
which item is selected. The radio group default selection is the
one defined in the settings.

Change-Id: Ib8d8716ec0038d2cd273423c756563680b84ae55
Reviewed-on: https://gerrit.libreoffice.org/34019Reviewed-by: Aleksandar Stefanović <theonewithideas@gmail.com>
Tested-by: Aleksandar Stefanović <theonewithideas@gmail.com>