Executor doesn't support " GROUP BY ... HAVING AVG(...) < ..."

[stonyw]

Similar with #1822

    def test_execute_group_by_having_aggr(self):
        tables = {
            "x": [
                {"a": "a1", "b": 1},
                {"a": "a2", "b": 2},
                {"a": "a3", "b": 3},
                {"a": "a1", "b": 6},
                {"a": "a2", "b": 9},
                {"a": "a2", "b": 2},
            ],
        }
        schema = {
            "x": {
                "a": "VARCHAR",
                "b": "numeric",
            },
        }

        for sql, cols, rows in [
            ('select a from x group by a having max(b) > 4', ["a"], [('a1',), ('a2',)]),  # FAILED
            ('select a from x group by a having avg(b) < 4', ["a"], [('a1',), ('a3',)]),  # FAILED
            ('select a from x group by a having count(*) = 2', ["a"], [('a1',)]),  # FAILED
        ]:
            with self.subTest(sql):
                result = execute(sql, schema=schema, tables=tables)
                self.assertEqual(result.columns, tuple(cols))
                self.assertEqual(result.rows, rows)