Notify the user when an unsupported accessory is attached

This CL pops up a notification to the user when the device does not
support Analog Type-C headphones but the user connects one.
i.e when the Usb port status reports currentMode=audio_acc, but
audio_acc is not present in the supportedModes list.

Bug: 36604276
Test: Manually test inserting an Audio accessory
Change-Id: If514b9f238da196a7157e1aacb6d7690fde66f21
diff --git a/proto/src/system_messages.proto b/proto/src/system_messages.proto
index 53b3fe9..ac544e8 100644
--- a/proto/src/system_messages.proto
+++ b/proto/src/system_messages.proto
@@ -180,6 +180,9 @@
     // Package: android
     NOTE_FOREGROUND_SERVICES = 40;
 
+    // Inform the user that the connected audio accessory is not supported
+    NOTE_USB_AUDIO_ACCESSORY_NOT_SUPPORTED = 41;
+
     // ADD_NEW_IDS_ABOVE_THIS_LINE
     // Legacy IDs with arbitrary values appear below
     // Legacy IDs existed as stable non-conflicting constants prior to the O release