media-session: add option to configure suspend timeout

Set the property on the node and use the value when suspending the
node. a timeout of 0 disables suspend.

src/daemon/media-session.d/v4l2-monitor.conf

@@ -39,6 +39,7 @@ rules = [
                 #priority.driver   = 100
                 #priority.session  = 100
                 node.pause-on-idle = false
+                #session.suspend-timeout-seconds = 5      # 0 disables suspend
             }
         }
     }