remove user argument. Use arcgisutils check_token_has_user()

[JosiahParry]

Checklist

• [x] update NEWS.md
• [x] documentation updated with devtools::document()
• [x] devtools::check() passes locally

Changes

This PR removes the user arguments from publishing functions. The user is now fetched from the auth token.

Follow up tasks

• [ ] revist r.esri.com authorization document