Update SSB stack to remove gossip APIs

[staltz]

Here's a big issue that covers a lot of TODOs in order to move away from ssb-gossip and adopt ssb-conn.

• [ ] Patchcore
  • patchcore/sbot.js should replace sbot.gossip.peers (a sync api) with ssb.conn.peers (a source api), should pull.drain that and update localPeers and connectedPeers
• [ ] Patchcore
  • patchcore/sbot.js should expose a new api called stagedPeers, similar to localPeers and connectedPeers, based on ssb.conn.stagedPeers (a source api)
• [ ] Patchcore
  • patchcore/sbot.js should replace gossipConnect with connConnect, replace sbot.gossip.connect with sbot.conn.connect
• [ ] ssb-ahoy
  • ssb-ahoy/views/replication should replace server.gossip.connect with server.conn.connect
• [ ] ssb-invite
  • ssb-invite should replace server.gossip.add with server.gossip.remember
• [ ] ssb-replicate
  • ssb-replicate should replace ssbServer.gossip.peers (a sync api) with ssbServer.conn.peers (a source api), pull.filter that to have only type==='lan' and truthy .key, pull.drain that, and request() replication
• [ ] ssb-ebt
  • ssb-ebt/index.js should remove the sbot.gossip.disconnect call because ssb-conn's scheduler automatically makes sure that blocked peers will never be connected to
• [ ] ssb-device-address
  • ssb-device-address/index.js should replace sbot.gossip.add/remove with sbot.conn.remember/forget, notice the TODO comment in ssb-device-address, ssb-conn supports multiserver addresses
• [ ] ssb-friend-pub
  • ssb-friend-pub/index.js should replace sbot.gossip.add/remove with sbot.conn.remember/forget