Provide a way to output which hosts a workspace will run against

[m4wh6k]

The boardwalk CLI will determine which hosts "need work" based upon Job preconditions and remote state. This determination is only made at runtime when the run or check subcommands are used. We've had circumstances where it would be convenient to simply output which hosts will be worked on, potentially in a table format that explains why hosts will be worked on or not.