examples: add basic app metadata to all existing examples.

examples/audio/02-simple-playback-callback/simple-playback-callback.c

@@ -53,6 +53,8 @@ SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[])
 {
     SDL_AudioSpec spec;
 
+    SDL_SetAppMetadata("Example Simple Audio Playback Callback", "1.0", "com.example.audio-simple-playback-callback");
+
     if (!SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO)) {
         SDL_Log("Couldn't initialize SDL: %s", SDL_GetError());
         return SDL_APP_FAILURE;