Add basic resize functionality

Addresses #3947
See https://codeberg.org/gitnex/GitNex/commit/9e352df1ed7d1d285fde61632822e2db5d128f16
See https://developer.samsung.com/samsung-dex/modify-optimizing.html#Enabling-Multi-Window-support

app/src/main/AndroidManifest.xml

@@ -23,10 +23,12 @@
         android:logo="@mipmap/ic_launcher"
         android:requestLegacyExternalStorage="true"
         android:theme="@style/OpeningTheme"
+        android:resizeableActivity="true"
         tools:ignore="AllowBackup">
         <activity
             android:name=".MainActivity"
             android:label="@string/app_name"
+            android:configChanges="orientation|screenSize|smallestScreenSize|density|screenLayout|uiMode|keyboard|keyboardHidden|navigation"
             android:launchMode="singleTask">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
@@ -334,5 +336,11 @@
         <service
             android:name=".RouterActivity$FetcherService"
             android:exported="false" />
+
+        <!-- see https://github.com/TeamNewPipe/NewPipe/issues/3947 -->
+        <!-- Version < 3.0. DeX Mode and Screen Mirroring support -->
+        <meta-data android:name="com.samsung.android.keepalive.density" android:value="true"/>
+        <!-- Version >= 3.0. DeX Dual Mode support -->
+        <meta-data android:name="com.samsung.android.multidisplay.keep_process_alive" android:value="true"/>
     </application>
 </manifest>