DbTool: Add method isConnected()

refs #9460

modules/setup/library/Setup/Utils/DbTool.php

@@ -204,6 +204,16 @@ class DbTool
         }
     }
 
+    /**
+     * Return whether a connection with the server has been established
+     *
+     * @return  bool
+     */
+    public function isConnected()
+    {
+        return $this->pdoConn !== null;
+    }
+
     /**
      * Establish a connection with the database or just the server by omitting the database name
      *