Update runner to handle Dotcom/runner-admin based registration flow (#2487)

src/Sdk/DTWebApi/WebApi/Runner.cs

@@ -0,0 +1,18 @@
+using Newtonsoft.Json;
+
+namespace GitHub.DistributedTask.WebApi
+{
+    public class Runner
+    {
+        /// <summary>
+        /// Name of the agent
+        /// </summary>
+        [JsonProperty("name")]
+        public string Name
+        {
+            get;
+            internal set;
+        }
+
+    }
+}