Add SystemMessages protos to Connectivity

This follows the model used for the same protos by the Wifi module in
service-wifi.

SystemMessageProto is used by NetworkNotificationManager to define IDs
for notifications that are also counted in system notification metrics.

Bug: 171860710
Test: m
Change-Id: Iec674913fad9ad59c04249714a08b5a0d8ab0f84
diff --git a/service/jarjar-rules.txt b/service/jarjar-rules.txt
index a7b419b..5caa11b 100644
--- a/service/jarjar-rules.txt
+++ b/service/jarjar-rules.txt
@@ -12,3 +12,6 @@
 # the one in com.android.internal.util
 rule android.util.IndentingPrintWriter* android.connectivity.util.IndentingPrintWriter@1
 rule com.android.internal.util.** com.android.connectivity.util.@1
+
+rule com.android.internal.messages.** com.android.connectivity.messages.@1
+rule com.google.protobuf.** com.android.connectivity.protobuf.@1