Implement L2 load balancing service

Including event/listener, CLI support

Change-Id: I26f1da578a72f5b3ead413aa5155233fbf9ab2b6
diff --git a/tools/build/bazel/modules.bzl b/tools/build/bazel/modules.bzl
index 1872d2b..8ddb02e 100644
--- a/tools/build/bazel/modules.bzl
+++ b/tools/build/bazel/modules.bzl
@@ -160,6 +160,7 @@
     "//apps/flowanalyzer:onos-apps-flowanalyzer-oar",
     "//apps/intentsync:onos-apps-intentsync-oar",
     "//apps/influxdbmetrics:onos-apps-influxdbmetrics-oar",
+    "//apps/l2lb:onos-apps-l2lb-oar",
     "//apps/metrics:onos-apps-metrics-oar",
     "//apps/mfwd:onos-apps-mfwd-oar",
     "//apps/mlb:onos-apps-mlb-oar",