[Thread] add demoapp for Thread network APIs

A screenshot of the demo app:
![](https://screenshot.googleplex.com/AsiYKPzG4nJpr6x.png)

Bug: 273227725
Change-Id: I8d9bcf00bb54d3f152c436b56df919d967c5b71b
diff --git a/thread/demoapp/res/navigation/nav_graph.xml b/thread/demoapp/res/navigation/nav_graph.xml
new file mode 100644
index 0000000..472d1bb
--- /dev/null
+++ b/thread/demoapp/res/navigation/nav_graph.xml
@@ -0,0 +1,35 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2023 The Android Open Source Project
+
+     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.
+-->
+
+<navigation xmlns:android="http://schemas.android.com/apk/res/android"
+            xmlns:tools="http://schemas.android.com/tools"
+            xmlns:app="http://schemas.android.com/apk/res-auto"
+            android:id="@+id/nav_graph"
+            app:startDestination="@+id/thread_network_settings" >
+    <fragment
+        android:id="@+id/thread_network_settings"
+        android:name=".ThreadNetworkSettingsFragment"
+        android:label="Thread Network Settings"
+        tools:layout="@layout/thread_network_settings_fragment">
+    </fragment>
+
+    <fragment
+        android:id="@+id/connectivity_tools"
+        android:name=".ConnectivityToolsFragment"
+        android:label="Connectivity Tools"
+        tools:layout="@layout/connectivity_tools_fragment">
+    </fragment>
+</navigation>