files-view: Show starring only for indexed (by default) files
Currently the star menu item is shown for every file in the system, however when a file is not indexed by tracker this operation fails.
We cannot set Tracker to index the file and wait for Tracker to index it, since that happens in an idle and Tracker doesn't queue the operation of starring.
There is no easy solution for this, so for now we will show the star menu item for indexed (by default) locations, which are the XDG folders, otherwise we will hide the item.
A better solution needs to be researched for 3.30, but this will do for now.
Related #243 (closed)