SettingsBackupAgent: notify of apBand conversion

Added support to notify user of a change to their softap configuration
preferences after being restored via SettingsBackupAgent.

Bug: 80251951
Test: frameworks/opt/net/wifi/tests/wifitests/runtests.sh
Test: manually confirmed configs are converted for different device
Change-Id: I4cec15549d694cdb1a7b09f1426d027eec021122
diff --git a/proto/src/system_messages.proto b/proto/src/system_messages.proto
index a9a14ca..fba639c 100644
--- a/proto/src/system_messages.proto
+++ b/proto/src/system_messages.proto
@@ -212,6 +212,10 @@
     // Package: android
     NOTE_AUTO_SAVER_SUGGESTION = 49;
 
+    // Notify the user that their softap config preference has changed.
+    // Package: android
+    NOTE_SOFTAP_CONFIG_CHANGED = 50;
+
     // 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