Expose the document "filename" for the current assignment

Explore two different approaches:

- Expose this a JSConfig options and let the LMS front end forward it to the client
- Send it over to Via (using a query paramter) and expose it as a HTML in the Via document.

### Different document sources:

- LMS files (Canvas, D2L and Blackboard hosted PDFs)

For these we have the file name stored in the LMS DB

- Google drive and One Drive

For these we might have to start capturing the file name during the assignment configuration.