Replace scheduler-specific command-line options

[vkarak]

The --partition, --account, --nodelist etc. options are actually scheduler-specific and, in my opinion, they should not be part of the command-line interface. Instead, the should be passed through a more generic mechanism such as the --job-option switch. There are advantages and disadvantages to what I suggest here:

Pros:

• Cleaner command-line
• Less implementation overhead for scheduler backends, since the user is responsible for passing the correct backend options in the special case that he wants to modify how an access to a specific partition is gained. A backend implementor need not be an expert of the scheduler.
• More uniform behaviour for the scheduler backends. For example, now we assume, at the supposedly scheduler-agnostic frontend, a SLURM-specific syntax for the node list.
• Avoid subtle bugs such as the one described in Revisit the way frontend options are passed to the scheduler backends #75.

Cons:

• We lose the automatic mapping of the command-line options to the different backends. This is only true for the --partition one. The rest are simply ignored by all other schedulers except Slurm.
• Perhaps more typing

[victorusu]

@vkarak, I think the overhead of typing more in the command line exists only when testing... Most of the ReFrame execution that we have seen is performed by robots...

[vkarak]

The problem is conceptual. You can't have command line options that essentially map to specific backend. This is wrong. You should still be able to pass these options, but in a more generic way.

[vkarak]

The fact that these options are there is pure legacy. They are coming from the pre-ReFrame regression framework.

[victorusu]

@vkarak, I completely agree with you!