Adds SystemMessage for CarrierNetworkNotification

Adds a separate field in SystemMessage class for Carrier Network
Notification, to be able to differentiate between Carrier and Open
network notifications in case we have both notifications at the same
time.

Bug: 69310016
Test: Builds successfully
Change-Id: I5c4f40640a924e39cf4c6a33825afcc1a5c9d4f9
diff --git a/proto/src/system_messages.proto b/proto/src/system_messages.proto
index 7c6019e..db70184 100644
--- a/proto/src/system_messages.proto
+++ b/proto/src/system_messages.proto
@@ -196,6 +196,10 @@
     // Inform the user that unexpectedly rapid network usage is happening
     NOTE_NET_RAPID = 45;
 
+    // Notify the user that carrier Wi-Fi networks are available.
+    // Package: android
+    NOTE_CARRIER_NETWORK_AVAILABLE = 46;
+
     // 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