Tool: Fetch Assignment Submissions

[eriq-augustine]

Create a tool to fetch the actual submission files for an assignment. Allow filtering by students. Ensure that files are named by email.

It looks like each submission file(s) will have to be be downloaded one at a time (see below references). So we'll fetch a full assignment (including "attachments"), then go through the attachments and download one at a time.

Some references:

• https://community.canvaslms.com/t5/Canvas-Developers-Group/API-Download-all-assignment-submissions/td-p/206319
• https://community.canvaslms.com/t5/Canvas-Developers-Group/Assignment-API-submissions-download-url/m-p/74848
• https://github.com/ucfopen/canvasapi/discussions/634

[eriq-augustine]

Initial version complete in 3cd1c7e0f9e5f10007e7d7a7b153633ebeaa5536.