Character set REGEXP syntax (ie. 'N[1,3]') not supported in Dolt

Consider the following table and data

```
CREATE TABLE IF NOT EXISTS `person` (`id` INTEGER AUTO_INCREMENT NOT NULL PRIMARY KEY, `name` VARCHAR(255) NOT NULL);
INSERT INTO `person` (`name`) VALUES ('n1');
INSERT INTO `person` (`name`) VALUES ('n2');
INSERT INTO `person` (`name`) VALUES ('n3');
```

Consider the following query

```SQL
SELECT `t1`.`id`, `t1`.`name` FROM `person` AS `t1` WHERE (`t1`.`name` REGEXP 'N[1,3]') ORDER BY `t1`.`name`;
```
MySQL Returns

```
+----+------+
| id | name |
+----+------+
| 1 | n1 |
| 3 | n3 |
+----+------+
```

Dolt returns the empty set