[Python] Add 'names' option to read_csv

[Tishj]

This PR fixes #8857

The PR also mentions auto_detect but that isn't supported.
read_csv will always auto detect currently.

We add support for the names parameter, as an Optional[List[str]], and this plays nicely with the existing dtype parameter.

Misc:

This PR also fixes a slight bug in dtype, as it cast the type parameter to DuckDBPyType but then didn't use this result, instead it just used str(type), which made dtype fail if anything other than a str | DuckDBPyType was provided.
Now things like int and str which can be implicitly cast to DuckDBPyType also work i.e

        rel = con.read_csv(
            file,
            names=['a', 'b', 'c'],
            dtype={
                'a': int,
                'b': bool,
                'c': str,
            },
        )

[Mytherin]

Thanks!