Drupal 10 Upgrade

[jonpugh]

In this project (drupal/commerce_nelnet)

• Add composer.json file. Add dependent modules to require section.
• Update module code to Drupal 10 using Rector.
• Complete any remaining upgrade tasks manually.
• Create a temporary composer project repo from drupal-composer/drupal-project and add this github repo as a composer repository and drupal/commerce_nelnet to requirements.

In the site code (https://bitbucket.org/investisdrupal/thunderbird/src/master/):

• Clone repo to github after removing large files. (Repo is 2.3 GB right now.)
• Test a site install with --existing-config.
• Enable and configure commerce_nelnet. Export working config.