Inconsistent spans for function calls

When using functions spans, it appears that sometimes the closing parenthesis is included, sometimes not.

Consider the following test:

```rust
#[test]
fn test_function_span() {
let sql = "SELECT database(), left(user(),instr(concat(user(),'@'),'@')-1);";
let r = Parser::parse_sql(&crate::dialect::MySqlDialect {}, sql).unwrap();

let query = match &r[0] {
crate::ast::Statement::Query(q) => q,
_ => panic!("Expected query"),
};

let select = match query.body.as_ref() {
crate::ast::SetExpr::Select(s) => s,
_ => panic!("Expected select"),
};

let database_func = match &select.projection[0] {
crate::ast::SelectItem::UnnamedExpr(crate::ast::Expr::Function(func)) => func,
_ => panic!("Expected function expression"),
};
let span = database_func.span();
assert_eq!(span.start, (1, 8).into());
assert_eq!(span.end, (1, 17).into()); // fails here

let left_func = match &select.projection[1] {
crate::ast::SelectItem::UnnamedExpr(crate::ast::Expr::Function(func)) => func,
_ => panic!("Expected function expression"),
};
let span = left_func.span();
assert_eq!(span.start, (1, 20).into());
assert_eq!(span.end, (1, 63).into());
}
```

In both cases, we're testing if the closing parenthesis is included in the span. The first span test for `database_func` fails:

```diff
Diff < left / right > :
-Location(1,16)
+Location(1,17)
```

If I comment that part, the second pair of span assertions passes correctly.

In other words, it seems that we only include closing parentheses for function calls with arguments, but not if there's no argument.

Related: #1548 #1563 #1676

Comece com o caso test_function_span fornecido usando Parser::parse_sql e MySqlDialect e, em seguida, rastreie como os spans de função são produzidos para database() e left(...). Compare os limites dos spans para chamadas com e sem argumentos. Está concluído quando ambas as assertions incluírem consistentemente o parêntese de fechamento e o teste passar.

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