Add --wait flag for Slurm mode.

[mbobrovskyi]

What would you like to be added:

• An option to wait for the Slurm job to finish its execution.
• A functionality to cancel / interrupt the job execution if the kjob create slurm --wait command execution is interrupted (for instance using CTRL+C) should stop a related Kubernetes job.
• An option to pipe the output from the executed pods to the console (this can be done for instance using kubectl logs -f job/job_name --all-containers=true).

Why is this needed:

Completion requirements:

This enhancement requires the following artifacts:

• Design doc
• API change
• Docs update

The artifacts should be linked in subsequent comments.

[mbobrovskyi]

cc: @IrvingMg @mwysokin @mimowo

[mbobrovskyi]

/assign @IrvingMg