Parameterized queries

This fails to parse, but it can be successfully executed by SQLite (after providing a value for the parameter):

```
#[test]
fn go() {
use sqlparser::dialect::SQLiteDialect;
use sqlparser::parser::Parser;

let sql = "select * from test_table where test_column = ?;";

let dialect = SQLiteDialect {}; // or AnsiDialect, or your own dialect ...

let ast = Parser::parse_sql(&dialect, sql).unwrap();

println!("AST: {:#?}", ast);
}
```

Any idea why I get this error message?:

_called `Result::unwrap()` on an `Err` value: ParserError("Expected an expression, found: ?")
thread 'dynamic_queries::go' panicked at 'called `Result::unwrap()` on an `Err` value: ParserError("Expected an expression, found: ?")',_

Start by reproducing the failure through Parser::parse_sql with SQLiteDialect and the parameterized query shown in the issue. Read the parser's expression handling around the `?` token and review the comment thread for the intended parameter representation. Done means the supported dialect behavior is clarified or implemented and covered by a regression test for this query.

Written by the indexing model from the issue text.