added failling PdoStatementObjectType test

[staabm]

refs #282 (comment)

this should also make phpstan-dba analysis possible across method boundaries.
atm all parts required for the inference need to be accessible from a single method.

I guess cases like

    public function querySelected(PDO $pdo): PDOStatement
    {
        return $pdo->query('SELECT email, adaid, gesperrt, freigabe1u1 FROM ada');
    }

    public function fetch(PDO $pdo):array {
       $stmt = $this->querySelected($pdo);
       return $stmt->fetch();
    }

    public function workWithData(PDO $pdo) {
       $data = $this->fetch($pdo);
       assertType('string', $data['email']);
    }

should work after we use the ObjectType properly