Implement of job interface to render a project via ARTIST

Allow whitelisted users to render their projects via ARTIST, replacing the current, mocked job interface which returns only a dummy status and result.

A rough outline of the steps (to be refined):
- [ ] Organizational: HPC access etc
- [ ] Implement slurm interaction to submit ARTIST jobs, get the current status, and process the results
- [ ] Implement workflow to whitelist users and check user privileges before submitting jobs
- [ ] Update and extend the job interface tests

Start by reading the current mocked job interface and the existing job interface tests. Then map the required workflow for whitelisting users, checking privileges, submitting ARTIST jobs through Slurm, tracking status, and processing results. Done means the mocked status and result are replaced, access is enforced, and the tests cover the updated workflow.

Written by the indexing model from the issue text.