iOS: Update diagnostic screen on state update

Summary: Update the diagnostic screen whenever the sonar state changes.

Reviewed By: priteshrnandgaonkar

Differential Revision: D9218765

fbshipit-source-id: 654a35e309cb43df18bc8c8a645d469eddc1031d

iOS/SonarKit/FlipperStateUpdateListener.h

@@ -0,0 +1,14 @@
+/*
+ *  Copyright (c) 2018-present, Facebook, Inc.
+ *
+ *  This source code is licensed under the MIT license found in the LICENSE
+ *  file in the root directory of this source tree.
+ *
+ */
+#ifdef FB_SONARKIT_ENABLED
+
+@protocol FlipperStateUpdateListener
+- (void)onUpdate;
+@end
+
+#endif