[CORD-2785] Refactor McastHandler and move to separated folder

Change-Id: I1f8ef7d51d57c90c4d29d79fa7e1ac9d0dbd4676
(cherry picked from commit 004d7cf78bf0228e23cbd17d19b2856c339c53e8)
diff --git a/apps/segmentrouting/app/src/main/java/org/onosproject/segmentrouting/SegmentRoutingService.java b/apps/segmentrouting/app/src/main/java/org/onosproject/segmentrouting/SegmentRoutingService.java
index fa7b7d6..759495b 100644
--- a/apps/segmentrouting/app/src/main/java/org/onosproject/segmentrouting/SegmentRoutingService.java
+++ b/apps/segmentrouting/app/src/main/java/org/onosproject/segmentrouting/SegmentRoutingService.java
@@ -22,6 +22,7 @@
 import org.onosproject.net.Link;
 import org.onosproject.net.PortNumber;
 import org.onosproject.segmentrouting.grouphandler.NextNeighbors;
+import org.onosproject.segmentrouting.mcast.McastRole;
 import org.onosproject.segmentrouting.pwaas.L2Tunnel;
 import org.onosproject.segmentrouting.pwaas.L2TunnelHandler;
 import org.onosproject.segmentrouting.pwaas.L2TunnelPolicy;
@@ -215,7 +216,7 @@
      * @param mcastIp the group ip
      * @return the mapping mcastIp-device to mcast role
      */
-    Map<McastStoreKey, McastHandler.McastRole> getMcastRoles(IpAddress mcastIp);
+    Map<McastStoreKey, McastRole> getMcastRoles(IpAddress mcastIp);
 
     /**
      * Returns the associated paths to the mcast group.