Support VPN over any native tethering

First big refactoring of this app.

mobile/src/main/res/layout/listitem_interface.xml

@@ -0,0 +1,44 @@
+<?xml version="1.0" encoding="utf-8"?>
+<layout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools">
+    <data>
+        <variable
+            name="data"
+            type="be.mygod.vpnhotspot.TetheringFragment.Data"/>
+    </data>
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:focusable="true"
+        android:background="?android:attr/selectableItemBackground"
+        android:paddingBottom="8dp"
+        android:paddingEnd="16dp"
+        android:paddingStart="16dp"
+        android:paddingTop="8dp">
+
+        <ImageView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:src="@{data.icon}"
+            tools:src="@drawable/ic_device_network_wifi"/>
+
+        <Space
+            android:layout_width="8dp"
+            android:layout_height="0dp"/>
+
+        <Switch
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:clickable="false"
+            android:ellipsize="end"
+            android:focusable="false"
+            android:focusableInTouchMode="false"
+            android:gravity="center_vertical"
+            android:text="@{data.iface}"
+            android:checked="@{data.active}"
+            tools:text="wlan0"/>
+
+    </LinearLayout>
+</layout>