Support extension from hyperbee

[RangerMauve]

The js version has an extension that is supposed to speed up replication for queries.

It's defined here: https://github.com/holepunchto/hyperbee/blob/main/lib/extension.js

It might be good to implement this for compatibility or to see if replication can work reliably without it.

[cowlicks]

The extension appears to just iterate over all keys of the most recent tree. Which basically just updates the data to most recent version so it can be cached.