Change SLURM scheduler interface to group jobs into job arrays.

[nicolas-kuechler]

Currently, commands on Euler are scheduled individually per job, which may result in many (potentially short-running) jobs.
In this situation, SLURM advocates for using job arrays because it reduces the load on the scheduler.

We could modify the SLURM task submission component in the doe-suite to group all jobs of an experiment into a single large job array submission. This requires modifying the roles suite-scheduler-enqueue, suite-scheduler-remove, and suite-scheduler-status to change the interaction with SLURM.

• Euler Docs: https://scicomp.ethz.ch/wiki/Job_arrays
• Slurm Docs: https://slurm.schedmd.com/job_array.html