Add a dry run feature

**Is your feature request related to a problem? Please describe.**

It would be helpful to know what steps of a DAG *would* execute when caching is enabled.

**Describe the solution you'd like**

For an example like [this](https://hamilton.staged.apache.org/concepts/caching/#visualization), being able to visualize DAGs or query cache results prior to execution through any Driver function would be great.

I imagine I'm far from the first person to think about this, but I'm not seeing any prior discussion about it. Are there any foundational design issues that would make this difficult to implement?