Tracking issue for implementation of ADR 101 (#82), since it appears as though it is the better of the two solutions between the "push" companion (#73) and the "pull" companion.

All implementations will take place on feature branches so we can choose when to release them. Ideally we would release all major versions' pull companions simultaneously across all major release branches, if we choose to release them as new features for pre-existing releases.

• Implement ADR-101 PoC targeting main #816
• Decide whether to implement the pruning API via the existing JSON-RPC or gRPC interfaces on the v0.38.x and v0.37.x branches - We will implement the ADR via gRPC in experimental branches for both versions
• ADR-101: Backport to v0.38.x #1419
• ADR-101: Backport to v0.37.x #1420

Additional PRs that would make this work easier to implement and/or review:

• Remove the existing gRPC broadcast API #650