Add timer and submission deadline

[MrSerth]

As an instructor, I wish to set a timer for programming exercises similar to multiple-choice questions in openHPI. This should force participants to submit their results once the timer expired and provide them with a visual hint about the remaining time.

I guess we need to rethink the LTI connection and the parameters we get for this feature to work. As of now, we only decide based on the lis_outcome_url at the start whether the submission deadline passed or not. This is not sufficient for this feature to work.

[MrSerth]

While we don't have a timer yet, we allow setting a (dedicated) submission deadline in CodeOcean directly. This submission deadline is independent from the one provided in openHPI, but is shown to learners. Further, it can be used to introduce a penalty for late submissions, reducing the original score.