feat: add courseaccessrole events

[Zacharis278]

Description: Creates new data class and events for publishing information about the creation or removal of an LMS CourseAccessRole. We are not planning to account for the roles and permissions changes at this point, events would be based on how roles currently work.

This will be consumed by edx-exams to sync access to instructor tools and actions on the API.

Author concerns: These events will be used instead those added by https://github.com/openedx/openedx-events/pull/267. I plan to remove those in a separate PR since there is no plan to use those event definitions or supporting data classes.

Merge checklist:

• [ ] All reviewers approved
• [ ] CI build is green
• [ ] Version bumped
• [ ] Changelog record added
• [ ] Documentation updated (not only docstrings)
• [ ] Commits are squashed

Post merge:

• [ ] Create a tag
• [ ] Check new version is pushed to PyPI after tag-triggered build is finished.
• [ ] Delete working branch (if not needed anymore)

[Zacharis278]

thanks @felipemontoya. I don't have write access to merge this. Is that something you can do or do I need to ping a specific maintainer?

[mariajgrimaldi]

Done: https://github.com/openedx/openedx-events/releases/tag/v9.4.0