Start the client in background if activated by D-Bus

The nextcloud client can be started by any other application consuming libcloudproviers.
Make sure that the client won't pop-up if we open the file manager.

Signed-off-by: Corentin Noël <corentin.noel@collabora.com>

shell_integration/libcloudproviders/org.freedesktop.CloudProviders.service.in

@@ -1,4 +1,4 @@
 [D-BUS Service]
 Name=@LIBCLOUDPROVIDERS_DBUS_BUS_NAME@
-Exec=@APPLICATION_EXECUTABLE@
+Exec=@APPLICATION_EXECUTABLE@ --background