sds: Create participant state data structures

[adklempner]

1. Generate a Message interface from protobuf definition per the specification: https://github.com/vacp2p/rfc-index/blob/main/vac/raw/sds.md#message

2. Create ParticipantState class/interface to track:

   • Local Lamport timestamps per channel (Map<string, number>)
   • Bloom filters per channel (Map<string, BloomFilter>)
   • Outgoing message buffer per channel (Map<string, OutgoingMessage[]>)
   • Incoming message buffer per channel (Map<string, IncomingMessage[]>)
   • Local message ID logs per channel (Map<string, string[]>)

3. Add helper methods for state management:

   • Initialize state for new channels
   • Clean up state for removed channels
   • Access and update state efficiently
   • Maintain sorted order for message logs