Added Avanlonia frontend.

FrontendAvalonia/FrontendAvalonia.Android/Resources/drawable/splash_screen.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
+
+  <item>
+    <color android:color="@color/splash_background"/>
+  </item>
+
+  <item android:drawable="@drawable/icon"
+        android:width="120dp"
+        android:height="120dp"
+        android:gravity="center" />
+
+</layer-list>