Adds Folder Support to Autograding

[Tkaixiang]

Description

To be merged with Frontend #2765 and Grader #319

Changes

• Changed /assessments/:assessmentid/submit pipeline to return all files in an assessment when submitting it for auto grading
• Changed /grading/:submissionid/autograde as well

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update
• Code quality improvements

Checklist

• I have tested this code
• I have updated the documentation

This change does not caue any API changes for the frontend, but only a change in the JSON in the request sent to Lambda workers for auto grading.

❗❗❗Note: This code has not been tested in staging yet (with except AWS Lambdas)