Add strings & channel to be used for notification to review permissions.

Also changes the SYSTEM_CHANGES notification channel to be IMPORTANCE_DEFAULT (by deprecating the existing, unused one).

Bug: 225373531
Test: manual by forcing the notification to show

Change-Id: I9743fe08cccbd8b6a9e7b367e32fe3e597b81ec4
Merged-In: I9743fe08cccbd8b6a9e7b367e32fe3e597b81ec4
diff --git a/proto/src/system_messages.proto b/proto/src/system_messages.proto
index 177b080..dfa34bb 100644
--- a/proto/src/system_messages.proto
+++ b/proto/src/system_messages.proto
@@ -286,6 +286,10 @@
     // Package: android
     NOTE_MTE_OVERRIDE_ENABLED = 69;
 
+    // Inform the user of notification permissions changes.
+    // Package: android
+    NOTE_REVIEW_NOTIFICATION_PERMISSIONS = 71;
+
     // 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