feat: allow staggered reboot of K3s cluster nodes

[felix-seifert]

Proposed Changes

Without specifying any new options, the reboot workflow runs like before; master nodes just got another check for being online.

As an option, you can now specify if you want to have a staggered reboot, i.e. not so many machines rebooting concurrently. It is then also possible to add a wait after rebooting a single machine/a few machines. The instructions on how to set these two options should become clear when reading the documentation.

Checklist

• Tested locally --> Tried on own cluster
• Ran site.yml playbook
• Ran reset.yml playbook
• Did not add any unnecessary changes
• Ran pre-commit install at least once before committing
• 🚀