Enhancement request: Add author to all codelist versions

Summary

Not all codelist versions are created with an author.

What would you like to achieve?

Creating a codelist version in the "normal" way (via the "Create a codelist" page, or by creating a new version in a codelist that supports the builder) adds the user to the codelists as an author. Creating a codelist by uploading a new version (for older codelists that were created by csv uploads, or dm+d codelists until recently) uses the create_old_style_version action and doesn't include the author (also it easily could, from the request).

Who would benefit and how?

It's not obvious who created the last version of a codelist. A user may want to publish a version that's under-review, and it's impossible to find out who created it to see if there's a reason they haven't published it yet.
E.g. https://bennettoxford.slack.com/archives/C33TWNQ1J/p1760600078349889

Start in codelists/actions.py at create_old_style_version, following how the upload request supplies its user. Compare this path with normal codelist creation and builder version creation. Done means versions created through older CSV uploads and dm+d uploads include the creating user as an author.