Cherry pick gNMI and Stratum related changes to this branch

Cherry picked commits:
20211 Update gNMI version and build script
20247 [ONOS-7829] Implement AbstractGrpcClient and AbstractGrpcClientControl
20233 [ONOS-7141][ONOS-7142] Add GnmiClient and GnmiController
20234 Refactor OpenConfig gNMI device description descovery
20260 [ONOS-7831] Implement GnmiHandshaker
20270 Add Stratum driver

Change-Id: I81ad8bce45251af5909cfcac0edbcfd11c8ebf1d
diff --git a/tools/build/bazel/gnmi_BUILD b/tools/build/bazel/gnmi_BUILD
new file mode 100644
index 0000000..43cb693
--- /dev/null
+++ b/tools/build/bazel/gnmi_BUILD
@@ -0,0 +1,17 @@
+proto_library(
+    name = "gnmi_proto",
+    srcs = ["gnmi/gnmi.proto"],
+    deps = [
+        ":gnmi_ext_proto",
+        "@com_google_protobuf//:descriptor_proto",
+        "@com_google_protobuf//:any_proto",
+    ],
+    visibility = ["//visibility:public"],
+)
+
+
+proto_library(
+    name = "gnmi_ext_proto",
+    srcs = ["gnmi_ext/gnmi_ext.proto"],
+    visibility = ["//visibility:public"],
+)