Port Discovery API + DiscoveryLan #337
Description
What's the problem you want solved?
Earthstar v11 does not have the Discovery API or the DiscoveryLan driver. So there is no discovery or syncing over LAN.
Is there a solution you'd like to recommend?
Port the existing APIs to the new codebase. One thing which will need to be decided (and specified) is the scheme used to encrypt the messages sent over TLS. Another will be the subtypes broadcast over MDNS.