Command to mass-abort work requests and workflows

User story

As a user running an experiment, I started hundreds of work requests (or workflows) and figured out that I gave some bad parameters. I'd like to abort all work requests (or workflows) that I started at once.

As an administrator concerned with improper usage of the debusine servers, I want to abort all the work requests/workflows of a user who underestimated the resources required to complete their requests.

Error handling

Describe the various error/failure scenarios and the expected behaviour.

Implementation plan

Fill in this section with a rough plan of how the feature will be implemented in the code base. This does not have to be filled from the start but should be filled before writing any code. For larger changes, it might be wise to first write official design documentation. In those cases, you should put here links to the corresponding documentation once it has been merged.

Open questions

• Add any question that needs to be resolved before proceeding with implementation

Notes

This issue description can be modified to integrate feedback from comments and from associated merge requests.

(issue split off from #384 (closed))