✨ NEW: Add support for PBS

[mbercx]

Currently the scheduler has only been developed/tested with Slurm in mind. However, since HyperQueue also supports PBS, we should redesign some parts to be more general so both job managers can be supported.

[giovannipizzi]

Indeed, we should just mirror the options that HQ has already? Maybe we could have some metadata to say that that computer has SLURM and not PBS, but for now I would do it "dumb" and the user has to specify pbs or slurm as you do in the hq command line