[65-libyang-testutils] Added missing (or restored) keaexample module

src/lib/yang/tests/keaexample-module.yang

+module keaexample-module {
+  yang-version 1.1;
+  namespace "urn:ietf:params:xml:ns:yang:keaexample-module";
+  prefix tm;
+
+  import ietf-inet-types {
+    prefix inet;
+  }
+
+  organization "Sysrepo and ISC";
+  description
+    "ISC imported an example module from Sysrepo tests and adapted it
+     to kea testing regime.";
+  contact
+    "kea-dev@lists.isc.org";
+
+   container container {
+      config true;
+      list list {
+         leaf leaf {
+            type string;
+         }
+         leaf key1 {
+            type string;
+         }
+         leaf key2 {
+            type string;
+         }
+         key "key1 key2";
+      }
+   }
+}