idle_inhibit: Ignore inhibitors when locked

When a session is locked, no views are visible and there is no way to
interact with the user session. This means that all inhibitors based on
visibility - with the exception being inhibitors on the session lock
surfaces themselves - become inert, allowing the session to go idle.

The only inhibitor type on normal views that one could argue should
remain active is INHIBIT_IDLE_OPEN, but for now we disable all view
inhibitors regardless of type.

sway/tree/view.c

@@ -218,6 +218,10 @@ uint32_t view_configure(struct sway_view *view, double lx, double ly, int width,
 }
 
 bool view_inhibit_idle(struct sway_view *view) {
+	if (server.session_lock.lock) {
+		return false;
+	}
+
 	struct sway_idle_inhibitor_v1 *user_inhibitor =
 		sway_idle_inhibit_v1_user_inhibitor_for_view(view);