[Consensus] State Sync - Configuration & Entrypoints for Node State

[Olshansk]

Objective

Maintain the state (e.g. synching, synched, etc...) of the node for state sync & execution purposes. the consensus module will have a variable that maintains state. This will require a constant that indicates its state (synced, syncing, pacemaker). The consensus module should still control state sync but there should be no validation as part of this implementation.

Origin Document

State sync block by block design: #125

Goals

• A foundation for the full state sync implementation
• Configurations & a rough "state machine" for all the states involved in state sync

Deliverables

• Implementation of entrypoints into the different states required for state sync
  • Interfaces that show the lifecycle of syncing without implementing state sync fully
• At a minimum, enable "synching" and "synced" states
• Placeholders / TODOs for the real state sync implementation

Non-goals

• Actual implementation of state sync

General issue checklist

• Update the appropriate CHANGELOG
• Update the README
• If applicable, update the source code tree explanation
• If applicable, add or update a state, sequence or flowchart diagram using mermaid
• Update any relevant global documentation & references
• Document small issues / TODOs along the way

---

Creators: @jessicadaugherty @Olshansk