Add sorting for grading

[thortol]

Description

To be merged with Frontend #2893

For implementation decisions, see Frontend PR.

Changes

• Changed submissions_by_grader_for_index pipeline by adding user table, assessment.title and assessment.config_id
• Added sort_submission to sort the query in the pipeline

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

[coveralls]

coverage: 94.978% (-0.3%) from 95.295%
when pulling b1c1061 on thortol:add-sorting-for-grading
into 4e55b6a on source-academy:master.

[RichDom2185]

Is this PR ready?