Added BNG dashboard, disabled by default

Also, added BNG topic and dashboard activation in seba-ponsim-sdbng.yaml values file.

Change-Id: Ic188e7504d97681f4a96bd7e68acd0de3d874cbd
diff --git a/nem-monitoring/values.yaml b/nem-monitoring/values.yaml
index d7236e8..5b5a6c3 100644
--- a/nem-monitoring/values.yaml
+++ b/nem-monitoring/values.yaml
@@ -104,3 +104,4 @@
   aetherEdges: false
   aetherCentralPods: false
   aetherEdgePods: false
+  bng: false