Proposal: Expose job folder as a template variable

[mikemhenry]

Feature description

Make it easier for job output (std out and err) to end up in the job directory.

Proposed solution

Expose something like job_output_dir as a variable for templating. Right now this is the hack I use:

#SBATCH --output=workspace/{{ operations[0].job }}/job_%j.o
#SBATCH --error=workspace/{{ operations[0].job }}/job_%j.e

I consider this a hack since it will break on job bundling (we will have to disable this feature when using a job bundle since its not well defined where std out and err should go in a bundle) and it also assumes the path and name of the workspace folder.

I've got some ideas how to add this, but I'm worried about how bundles might make this a bit complicated.