Pretty Print toolbox configuration.

[benjamin-heasly]

Currently tbDeployToolboxes parses the given struct or JSON configuration and decides what to do with it. It's not always clear what it's going to do in advance.

It would help document the ToolboxToolbx and individual configurations if we could also "pretty print" a given configuration. This would write out in a friendly, human-readable way, how the given configuration would be processed.

This could be used to "dry run" a given configuration.

It could also be used as the basis for auto-generated documentation for how to install a toolbox, with or without the ToolboxToolbox.

It could also be used as the basis for documentation about the ToolboxToolbox itself, since we could include the pretty print output along with the usage examples.

As part of implementing this, we could add a describe method to the TbToolboxStrategy class. This would allow specific strategies to describe what they're going to do with a given record.