Move global admin controllers from Admin to SuperAdmin namespace

Backup, Update, Modules, and global Settings controllers (mail config,
PDF config, disk management, global settings) are application-wide features
not scoped to a company. Move them from Admin/ to SuperAdmin/ to match the
v3.0 UI structure where these live under Administration.

Company-scoped settings controllers remain in Admin/Settings/.

app/Http/Controllers/V1/SuperAdmin/Update/DownloadUpdateController.php

@@ -0,0 +1,37 @@
+<?php
+
+namespace App\Http\Controllers\V1\SuperAdmin\Update;
+
+use App\Http\Controllers\Controller;
+use App\Services\Update\Updater;
+use Illuminate\Http\Request;
+use Illuminate\Http\Response;
+
+class DownloadUpdateController extends Controller
+{
+    /**
+     * Handle the incoming request.
+     *
+     * @return Response
+     */
+    public function __invoke(Request $request)
+    {
+        if ((! $request->user()) || (! $request->user()->isOwner())) {
+            return response()->json([
+                'success' => false,
+                'message' => 'You are not allowed to update this app.',
+            ], 401);
+        }
+
+        $request->validate([
+            'version' => 'required',
+        ]);
+
+        $path = Updater::download($request->version);
+
+        return response()->json([
+            'success' => true,
+            'path' => $path,
+        ]);
+    }
+}