Add quick sync option for threads

[michaelsena]

Description

This feature would allow an app front end to sync only the last n messages in a thread or begin from a cold start with no sync.

This was a request from @joeykrug

[oed]

This feature is being built into orbitdb, but it's unclear on what timeline. This will allow the sync of the last n operations in the ipfs-log of orbitdb.

Depending on the use case it might make sense to not actually use threads at all. If the intention is to build a fast paced chat system it might be easier to just build that ontop of IPFS pubsub. This would however not allow to sync the last n messages easily however.