[Mode Controller] Support smooth transitions between consensus and state sync

[JoshLind]

Problem

When we move to the world of subcommittees, validators will move in and out of active consensus participation. Moreover, fullnodes may become validators (e.g., if they stake enough on-chain). However, today, nodes must be started up in either fullnode or consensus mode based on the node configuration file. Mode changes require restarts.

Solution

In an ideal world, a node would behave as a fullnode by default (i.e., actively synchronize the state of the blockchain) until the point where it recognizes that it is now in an active consensus state and then begin to participate in consensus. When the node falls out of consensus (e.g., the subcommittee) it should return back to synchronizing the blockchain state.

Tasks

(These are not in order of priority. Optional "nice to have" features are marked 😄)

TODO(joshlind): complete me!

[github-actions[bot]]

This issue is stale because it has been open 45 days with no activity. Remove the stale label or comment - otherwise this will be closed in 15 days.

[github-actions[bot]]

This issue is stale because it has been open 45 days with no activity. Remove the stale label or comment - otherwise this will be closed in 15 days.