Node configuration

[mzabaluev]

Decide which approach to managing node configuration do we want:

• a single well-defined format (or a serde schema uniformly mapped to JSON, YAML,... )
• a more abstract system with node config, possibly coming from a networked key-value space or similar.

Adjacent issues:

• Requirements from setup components for testing and deployment. Do we need readiness notification as a feature, or can this be managed by setup helpers before the node is started?
• Change notifications in a running node? Current thinking: not worth it, we can always roll over to another instance with the new config in the infrastructure.

[l-monninger]

I think a lot of this falls under #384 , but perhaps here we can instigate a pass on all of the configurables in each software unit.

[l-monninger]

Change notifications in a running node

I also do not think change notifications are clearly needed. However, relying on a notification-based setup task has been easier than before.

I do think other parts of the current the "manager" pattern are quite nice too. For example, waiting on a valid type contract then having all of the information available to the subsequent units thereafter makes implementations clearer and missing config crashes less likely.