Allow setting account via flag when submitting

[cbkerr]

Feature description

Discussed with @joaander today.

I would like to be able to set the account on the command line when submitting jobs through flow.

I'm setting it via environment variable, so signac-flow gives me this warning. I would like to be able to silence this warning.

Environment 'DeltaEnvironment' allows the specification of an account name that will be charged for jobs' compute time.
Set the account name with the command:

  $ signac config --global set 'flow.DeltaEnvironment.account' ACCOUNT_NAME

Proposed solution

This may be a good first issue.

Additional context

Other ways to set account:

• environment variable
• flow config
• custom template

[cbkerr]

Related issue discussed with @yuanzhou0827, you can't specify the partition in the config settings. Not sure if that would be helpful once you're on a certain cluster