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/drivers/stratum/src/main/resources/stratum-drivers.xml b/drivers/stratum/src/main/resources/stratum-drivers.xml
new file mode 100644
index 0000000..83fea1d
--- /dev/null
+++ b/drivers/stratum/src/main/resources/stratum-drivers.xml
@@ -0,0 +1,32 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  ~ Copyright 2017-present Open Networking Foundation
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<drivers>
+    <driver name="stratum" manufacturer="Open Networking Foundation"
+            hwVersion="master" swVersion="Stratum" extends="p4runtime,gnmi">
+        <behaviour api="org.onosproject.net.device.DeviceHandshaker"
+                   impl="org.onosproject.drivers.stratum.StratumHandshaker"/>
+    </driver>
+
+    <driver name="stratum-dummy" manufacturer="Open Networking Foundation"
+            hwVersion="Dummy" swVersion="Stratum" extends="stratum">
+        <behaviour api="org.onosproject.net.behaviour.PiPipelineProgrammable"
+                   impl="org.onosproject.drivers.stratum.dummy.StratumDummyPipelineProgrammable"/>
+        <property name="tableReadFromMirror">true</property>
+        <property name="actionGroupReadFromMirror">true</property>
+    </driver>
+</drivers>
+