Add VPN support with Mullvad WireGuard integration

app/src/main/res/drawable/btn_vpn_selector.xml

@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="utf-8"?>
+<selector xmlns:android="http://schemas.android.com/apk/res/android">
+    <item android:state_selected="true">
+        <shape android:shape="rectangle">
+            <solid android:color="#4CAF50"/>
+            <corners android:radius="8dp"/>
+        </shape>
+    </item>
+    <item>
+        <shape android:shape="rectangle">
+            <solid android:color="#FF5722"/>
+            <corners android:radius="8dp"/>
+        </shape>
+    </item>
+</selector>