Extract and publish p4runtime protocol utils in separate artifact

For consumption by third-party apps built via mvn

Change-Id: Ic9c1eccb2519b2952cdb632e1f07ccefbba00396
diff --git a/tools/build/publish-target-list b/tools/build/publish-target-list
index 517d902..64f6e67 100644
--- a/tools/build/publish-target-list
+++ b/tools/build/publish-target-list
@@ -23,6 +23,7 @@
     //protocols/bgp/bgpio:onos-protocols-bgp-bgpio
     //protocols/grpc/api:onos-protocols-grpc-api
     //protocols/p4runtime/api:onos-protocols-p4runtime-api
+    //protocols/p4runtime/utils:onos-protocols-p4runtime-utils
     //protocols/p4runtime/model:onos-protocols-p4runtime-model
     //protocols/p4runtime/proto:onos-protocols-p4runtime-proto
     //protocols/grpc/utils:onos-protocols-grpc-utils