Handle tunnel state change errors appropriately

This class should probably be renamed and moved, but I don't know to
what or where.

Signed-off-by: Samuel Holland <samuel@sholland.org>

app/src/main/res/layout/tunnel_detail_fragment.xml

@@ -5,6 +5,8 @@
 
     <data>
 
+        <import type="com.wireguard.android.fragment.TunnelController" />
+
         <import type="com.wireguard.android.model.Tunnel.State" />
 
         <import type="com.wireguard.android.util.ClipboardUtils" />
@@ -52,7 +54,7 @@
                     android:layout_alignBaseline="@+id/interface_title"
                     android:layout_alignParentEnd="true"
                     app:checked="@{tunnel.state == State.UP}"
-                    app:onBeforeCheckedChanged="@{() -> tunnel.setState(State.TOGGLE)}" />
+                    app:onBeforeCheckedChanged="@{TunnelController::setTunnelState}" />
 
                 <TextView
                     android:id="@+id/interface_name_label"

app/src/main/res/layout/tunnel_list_item.xml

@@ -4,6 +4,8 @@
 
     <data>
 
+        <import type="com.wireguard.android.fragment.TunnelController" />
+
         <import type="com.wireguard.android.model.Tunnel" />
 
         <import type="com.wireguard.android.model.Tunnel.State" />
@@ -47,6 +49,6 @@
             android:layout_alignBaseline="@+id/tunnel_name"
             android:layout_alignParentEnd="true"
             app:checked="@{item.state == State.UP}"
-            app:onBeforeCheckedChanged="@{() -> item.setState(State.TOGGLE)}" />
+            app:onBeforeCheckedChanged="@{TunnelController::setTunnelState}" />
     </RelativeLayout>
 </layout>

app/src/main/res/values/strings.xml

@@ -16,7 +16,6 @@
     <string name="edit">Edit</string>
     <string name="endpoint">Endpoint</string>
     <string name="error_down">Error bringing down WireGuard tunnel</string>
-    <string name="error_su">WireGuard currently requires root access</string>
     <string name="error_up">Error bringing up WireGuard tunnel</string>
     <string name="generate">Generate</string>
     <string name="hint_automatic">(auto)</string>