[Feature Requests] License Integration to code files

When `nbdev_export`, it would be awesome if it automatically export the LICENSE to the beginning of the exported python file automatically. What about making an option to `nbdev_export` cli?

It would also be nice if we can read the quarto raw cell's infomartion about the author infomation to change the license words.

Start at the nbdev_export CLI entry point and trace how notebooks become exported Python files. Determine how an optional LICENSE export and Quarto raw-cell author information should be represented. Done means the license can be included at the beginning of exported files and its wording can reflect the author information when provided.

Written by the indexing model from the issue text.