Unable to parse 'max' for optional precision column with MS Sql dialect

The following is a valid MS Sql query, but cannot ne parsed due to the `varbinary` implementation.

Variable character-based columns, `nvarchar` and `varchar`, use a union type `CharacterLength` type that allows for either `IntegerLength` or `Max` values. The `varbinary` implementation needs a similar union, such as `BinaryLength` (reusing `CharacterLength` seems to have a naming mismatch).

```
#[test]
fn parse_ms_sql_varbinary_max(){
let sql = "CREATE TABLE example(VarBinaryMaxCol varbinary(max) not null);";
let parsed = ms().parse_sql_statements(sql);

assert!(parsed.is_ok());
}
```

从 varbinary 实现开始，并将其与 issue 中描述的 CharacterLength 处理进行比较。运行提供的 parse_ms_sql_varbinary_max 测试；完成的标准是包含 varbinary(max) 的 MS SQL CREATE TABLE 语句能够成功解析。

由索引模型根据 Issue 内容生成。