Python: introduce workflow checkpointing (#366)
* Add workflow checkpointing functionality.
* Reintroduce protocol that went missing during merge
* Checkpoint updates
* Fix ordering of checkpointing
* Cleanup
* Cleanup - thanks Copilot
* Cleanup - thanks Copilot
* State reset updates
* State reset updates 2
* Workflow fixes and updates. Addressed PR feedback
* A few updates
Evan Mattson