feat: add attachView method

Author: mychidarko

src/App.php

@@ -178,6 +178,15 @@ public function attach(callable $code)
         $this->setupErrorHandler();
     }
 
+    /**
+     * Attach a view engine to Leaf
+     * @param mixed $view The view engine to attach
+     */
+    public function attachView($view)
+    {
+        Config::attachView($view);
+    }
+
     /**
      * Evade CORS errors
      *