Reproducible Workflows

## Background
Often, it is still hard to drag in a workflow JSON and just expect it to work. Models are missing. Input files are missing. Custom nodes are not installed or the wrong version.

## In Scope

- Add additional information to saved workflows and workflows embedded in outputs.
- Information that helps find the model (e.g. hash)
- Information that helps load the same set of custom nodes
- Information that helps update to the same version of ComfyUI
- Information that helps install the same version of Python libraries