output/PipeWire: set app icon

Closes #1564

src/output/plugins/PipeWireOutputPlugin.cxx

@@ -514,6 +514,7 @@ PipeWireOutput::Open(AudioFormat &audio_format)
 				       PW_KEY_MEDIA_CATEGORY, "Playback",
 				       PW_KEY_MEDIA_ROLE, "Music",
 				       PW_KEY_APP_NAME, "Music Player Daemon",
+				       PW_KEY_APP_ICON_NAME, "mpd",
 				       nullptr);
 
 	pw_properties_setf(props, PW_KEY_NODE_NAME, "mpd.%s", name);