container.yaml: Add gvfsd access
    
    This fixes the following warnings on the command line:
    
    GVFS-WARNING **: 13:10:18.232: The peer-to-peer connection failed: Error when getting information for file “/run/user/1000/gvfsd”: No such file or directory. Falling back to the session bus. Your application is probably missing --filesystem=xdg-run/gvfsd privileges.