Extract and publish p4runtime protocol utils in separate artifact

For consumption by third-party apps built via mvn

Change-Id: Ic9c1eccb2519b2952cdb632e1f07ccefbba00396
diff --git a/protocols/p4runtime/BUILD b/protocols/p4runtime/BUILD
index 39f6403..5db0ebe 100644
--- a/protocols/p4runtime/BUILD
+++ b/protocols/p4runtime/BUILD
@@ -3,6 +3,7 @@
     "//protocols/p4runtime/ctl:onos-protocols-p4runtime-ctl",
     "//protocols/p4runtime/model:onos-protocols-p4runtime-model",
     "//protocols/p4runtime/proto:onos-protocols-p4runtime-proto",
+    "//protocols/p4runtime/utils:onos-protocols-p4runtime-utils",
 ]
 
 onos_app(