Sorting: Extracted URL sort helper to own class

Was only used in one place, so didn't make sense to have extra global
helper clutter.

app/Activity/Controllers/AuditLogController.php

@@ -5,6 +5,7 @@ namespace BookStack\Activity\Controllers;
 use BookStack\Activity\ActivityType;
 use BookStack\Activity\Models\Activity;
 use BookStack\Http\Controller;
+use BookStack\Sorting\SortUrl;
 use BookStack\Util\SimpleListOptions;
 use Illuminate\Http\Request;
 
@@ -65,6 +66,7 @@ class AuditLogController extends Controller
             'filters'       => $filters,
             'listOptions'   => $listOptions,
             'activityTypes' => $types,
+            'filterSortUrl' => new SortUrl('settings/audit', array_filter($request->except('page')))
         ]);
     }
 }