MS SQL create table parse error

This is a mirror of[ the C# issue found here](https://github.com/TylerBrinks/SqlParser-cs/issues/16)

MS SQL parsing expects a comma after `primary key` and does not accept the `identity` keyword

```
#[test]
fn parse_ms_sql_create_column_with_identity(){
let sql = "create table T_Users(id bigint primary key identity, username varchar(255) not null);";
ms().verified_only_select(sql);
}
```

Read the `parse_ms_sql_create_column_with_identity` reproduction and run it through `ms().verified_only_select(sql)`. Trace the MS SQL parsing path for the supplied CREATE TABLE statement, using the linked C# issue for context; done means the test accepts `primary key identity` without requiring a comma.

Written by the indexing model from the issue text.