Add visibility option to hide tests after the due date

[joelostblom]

Is your feature request related to a problem? Please describe.
I would like the option to hide some tests after the due date but show them before the due date. These are public tests that are useful for students to see when they submit to know everything went OK and they submitted the corrrect file. When showing all hidden tests after the due date the public tests show up twice, both in their own separate section and under their respective question, which can be confusing as student might think they count twice.

Describe the solution you'd like
Add an option to "hide after due date" to the current test visibility cases at https://gradescope-autograders.readthedocs.io/en/latest/specs/#controlling-test-case-visibility

Describe alternatives you've considered
Currently I need to maunally upload a new autograder after the deadline to fix this.

Additional context
See ucbds-infra/otter-grader#561 and the issues linked there for more details

[joelostblom]

Any feedback or thoughts on this? It can lead to some confusion to always show these results since public tests show up twice and uploading a new autograder after the submission deadline is not convenient.