Systemd services & timers for custom workflow

Fixes #570 (closed)

This ensures that the auth token is written to the console log as soon as the container is started (or restarted), and then every hour.

How to Test

• Launch an instance with a workflow (try with both Ubuntu and Rocky)
• Ensure the token is written to the console log as soon as the notebook is running
• Restart the custom workflow service: systemctl restart custom-workflow.service
• Ensure that the new token is written to the console log a few seconds after the service is back up
• Wait till the top of the hour (*:00:00)
• Ensure that the same token is written to the console log

Screenshots

(If visual changes are introduced, show what they look like)

QA Checklist

• Any changes to 'widgets' in src/Style/Widgets/? If so:
  • Update src/Style/StyleGuide.elm showing example usage of that widget
• Were any app flags created, modified, or removed? If so:
  • Update config.js and all files in environment-configs/, including docker-config.js
  • Update "Runtime configuration options" documentation in README.md

Post-Merge Checklist

• Create follow-up issues for anything left over for another merge request
  • If any technical debt is introduced, assign these follow-up issues to the MR submitter