Add export_events route and controller action to export dummy CSV

[YoshwanPathipati]

• Added a new member route under course_offerings to export events.
• Created export_events method in CourseOfferingsController.
• Generates dummy CSV data for now.
• Verified route shows up via rails routes, and renders from https://opendsa-lti.localhost.devcom.vt.edu/course_offerings/2/export_events
• Getting an error due to find_attempts — looks unrelated to new code.

[awhicks]

Thank you for working on this! A couple of changes:

1. Bring back the ODSA_BRANCH arg in the Dockerfile
2. If possible, can you amend the commit to avoid pushing the file permission changes to all the script files, in particular, when you commit, make sure you git add only the files you intend to
3. I think we'll probably hold off getting this merged until you've implemented the queries for the database in the course offerings controller

Hopefully all that makes sense?

[YoshwanPathipati]

Updated the commit with Dockerfile ARG and cleaned up permissions. Holding this as a draft until database query for export_events is implemented.