Add memory option to script

[Bubballoo3]

What does this PR do?

Adds a memory option to the script option to request memory-per-node in MiB. Adds support for this attribute in the slurm adapter

Related issue

Fixes #952

Testing

• Tests included
• No tests needed — reason: ___

Checklist

• Follows project code style and conventions
• Documentation provided (if new feature, adapter or behavior change)
• This is a large feature and was discussed in an issue first (if applicable)

Anything else?

Still exploring documentation for other schedulers, so that will be incoming soon

[johrstrom]

Still exploring documentation for other schedulers, so that will be incoming soon

https://slurm.schedmd.com/rosetta.pdf

[johrstrom]

Seems fine to me.

[Bubballoo3]

See https://exaworks.org/psij-python/docs/v/0.9.10/.generated/index.html#resourcespecv1 as a reference for these changes. It only accepts memory as an integer number of bytes, which is why the helper method is required to take it from MiB to bytes

[Bubballoo3]

@johrstrom I think I have hit all the schedulers, but let me know if I am missing any that I should add. I currently have everything on the RosettaStone doc except LoadLeveler (which doesn't have a scheduler?) plus PSIJ. Adding Fujitsu would be nice but I haven't found docs anywhere and the link from @mnakao in #851 (comment) is no longer valid. But if you agree, I think this has enough breadth to move forward on.