As I'm thinking what to do of the CDC for now, I got thinking
a bit more about how to handle the log entry/state persisting split.
I think this makes more sense, it'll allow the log consensus module
to be bolted on top fairly cleanly.
Most operations apart from spans-related ones work. Using this as
a checkpoint -- the Python code is currently not really working,
I'm working to migrate to pretty much a full C++/go world.