SDFAB-104 Support routing via next hop in single leaf pair topology

The original design principle we adopted while implementing dual-homing is only recovering local failure using pair link.
Routing via next hop is a global thing recovered by updating ECMP hashing.
However, there is no spine in the single leaf pair setup so we need additional logic to recover this using pair link.

Change-Id: I3d648b139038be69656dd86b4c40d12bf10f50b2
diff --git a/impl/src/test/java/org/onosproject/segmentrouting/HostHandlerTest.java b/impl/src/test/java/org/onosproject/segmentrouting/HostHandlerTest.java
index 45d2b4d..e9cde67 100644
--- a/impl/src/test/java/org/onosproject/segmentrouting/HostHandlerTest.java
+++ b/impl/src/test/java/org/onosproject/segmentrouting/HostHandlerTest.java
@@ -231,7 +231,7 @@
         mockNetworkConfigRegistry.applyConfig(dev4Config);
 
         // Initialize Segment Routing Manager
-        SegmentRoutingManager srManager = new MockSegmentRoutingManager(NEXT_TABLE);
+        SegmentRoutingManager srManager = new MockSegmentRoutingManager(NEXT_TABLE, Maps.newHashMap());
         srManager.storageService = createMock(StorageService.class);
         expect(srManager.storageService.consistentMapBuilder()).andReturn(new TestConsistentMap.Builder<>()).anyTimes();
         expect(srManager.storageService.consistentMultimapBuilder()).andReturn(