Add support for character classes union intersection

```scala
pass("[a-d[m-p]]", "acn")
pass("[[a-z] && [b-y] && [c-x]]", "g")
pass("[a-z&&[def]]", "e")
pass("[a-z&&[^aeiou]]", "c")
fail("[a-z&&[^aeiou]]", "o")
pass("[a-z&&[^m-p]]", "c")
fail("[a-z&&[^m-p]]", "n")
```