Make notification icons and autocancel overlayable

Allow overlays to change the connectivity notification icons, and
whether the notifications are auto-cancelled.

This does not change default behavior, but is necessary to allow vendors
to adapt the notifications to their standards.

Bug: 173171709
Bug: 172048052
Test: atest NetworkNotificationManagerTest
      Added test overlay, verified icon replaced
Change-Id: Ibbb765a5e828b8b870cbfb81e89df2dbd2828be7
diff --git a/service/ServiceConnectivityResources/res/values/config.xml b/service/ServiceConnectivityResources/res/values/config.xml
index 70ddb9a..bf32ad5 100644
--- a/service/ServiceConnectivityResources/res/values/config.xml
+++ b/service/ServiceConnectivityResources/res/values/config.xml
@@ -111,4 +111,7 @@
          notification that can be dismissed. -->
     <bool name="config_ongoingSignInNotification">false</bool>
 
+    <!-- Whether to cancel network notifications automatically when tapped -->
+    <bool name="config_autoCancelNetworkNotifications">true</bool>
+
 </resources>