Waku Relay pubSub topic sharding

The goal is splitting the default Waku pubsub topic into several shard topics. This allows tuning the trade-off between bandwidth and anonymity, see anonymity trilemma. Per default, applications would be obilivous to the pubsub topic and only work with content topics. This improves anonymity and resilience, and reduces confusion. Applications should still be able to choose to introduce their own pubsub topics, which also should have an automatic sharing option

[ ] research efficient sharding approach with good anonymity properties
- basic idea: Content topics are mapped using consistent hashing. Like with DHTs, the hash space is split into parts, each covered by a Pubsub topic (mesh network) that carries content topics which are mapped into the respective part of the hash space.
[ ] research methods for topic shard discovery (shared with the discovery track)
- envisioned approach: successor of discv5 topic discovery
[ ] topic sharding raw RFC
[ ] topic sharding PoC implementation
[ ] research methods for avoiding hot / cold spot when mapping content topics to pubsub topics
[ ] update topic sharding raw RFC, including hot/cold spot mitigation
[ ] research log article on topic sharding

vacp2p / research

Waku Relay pubSub topic sharding #157