[kjobctl] Provide the name of the executed script in the "describe slurm"

[BluValor]

What would you like to be added: Add name of the source file of the script executed when creating a slurm job to the "describe slurm" output.

Why is this needed: "describe slurm" currently prints out the content of the executed script, but not the name of the source file of the script.

Completion requirements: The output of the "describe slurm" command should contain either:

• the name of the source file of the script
• the whole path to the source file of the script (aka the default argument of the "create slurm" command)

[mimowo]

Cc @mbobrovskyi

[mimowo]

Cc @mwysokin