Add optional args to ssh deployment for docker run arguments

[pl4nty]

In my case, this allowed adding Linux capabilities to run nsjail for TCP-based pwn chals.

[ColdHeat]

So I thought about this for awhile and I think this is possibly going in the wrong direction. Ideally everything needed to deploy a challenge should be in challenge.yml. I realize that currently sometimes that's not the case but I think it's the goal to strive for. Perhaps it makes sense to put deploy args somewhere in challenge.yml?

[pl4nty]

@ColdHeat that makes sense, I've swapped it for deploy_args in challenge.yml and updated the example. Currently only supports SSH deployments (docker run [deploy_args]), but this design could allow args for registry/cloud deployments if that's needed in future.