Trigger pipeconf deploy right after registration

Without waiting for the next pipeconf watchdog periodic probe.
To support this, this patch extends the PiPipeconfService to advertise
pipeconf registration events.

Change-Id: Ib44f1813bd37083c666a5e7980de320ce469c2d2
diff --git a/core/api/src/main/java/org/onosproject/net/pi/service/PiPipeconfListener.java b/core/api/src/main/java/org/onosproject/net/pi/service/PiPipeconfListener.java
new file mode 100644
index 0000000..11209e1
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/net/pi/service/PiPipeconfListener.java
@@ -0,0 +1,25 @@
+/*
+ * Copyright 2019-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.net.pi.service;
+
+import org.onosproject.event.EventListener;
+
+/**
+ * Listener of pipeconf events.
+ */
+public interface PiPipeconfListener extends EventListener<PiPipeconfEvent> {
+}