Add logout button to init screen

lib/ui/auth/init_screen.dart

@@ -3,6 +3,7 @@ import 'package:flutter/material.dart';
 
 // Package imports:
 import 'package:flutter_redux/flutter_redux.dart';
+import 'package:invoiceninja_flutter/utils/localization.dart';
 import 'package:redux/redux.dart';
 
 // Project imports:
@@ -12,6 +13,8 @@ import 'package:invoiceninja_flutter/redux/auth/auth_actions.dart';
 class InitScreen extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
+    final localization = AppLocalization.of(context)!;
+
     return StoreBuilder(
         onInit: (Store<AppState> store) =>
             store.dispatch(LoadStateRequest(context)),
@@ -21,9 +24,32 @@ class InitScreen extends StatelessWidget {
             child: Column(
               mainAxisSize: MainAxisSize.max,
               children: <Widget>[
+                Expanded(child: SizedBox()),
                 Expanded(
                   child: Center(child: Image.asset('assets/images/icon.png')),
                 ),
+                Expanded(
+                  child: Stack(
+                    alignment: Alignment.center,
+                    children: [
+                      SizedBox(
+                        height: 50,
+                        width: 100,
+                        child: Material(
+                          child: ElevatedButton(
+                            child: Text(
+                              localization.logout.toUpperCase(),
+                              style: TextStyle(color: Colors.white),
+                            ),
+                            onPressed: () {
+                              store.dispatch(UserLogout());
+                            },
+                          ),
+                        ),
+                      ),
+                    ],
+                  ),
+                ),
                 SizedBox(
                   height: 4.0,
                   child: LinearProgressIndicator(),