botserv: bot registry + BOT ADD/DEL/LIST (first slice)

Adds BotServ as a new module crate (fedserv-botserv) and a persisted bot
registry: a typed Bot{nick,user,host,gecos} threaded through the event log
(new bots map folded in apply, snapshotted, Local scope). BOT ADD/DEL/LIST
gated on the typed Priv::Admin. BotServ is a default service (uid suffix
AAAAAD). Next slices: introduce bots on the network, ASSIGN to channels, and
in-channel fantasy commands. Data + oper-gated engine tests.

src/grpc.rs

@@ -135,7 +135,9 @@ fn to_wire(entry: &LogEntry) -> Option<ReplicationEvent> {
         | Event::ChannelSettingsSet { .. }
         | Event::ChannelTopicSet { .. }
         | Event::ChannelSuspended { .. }
-        | Event::ChannelUnsuspended { .. } => return None,
+        | Event::ChannelUnsuspended { .. }
+        | Event::BotAdded(_)
+        | Event::BotRemoved { .. } => return None,
     };
     Some(ReplicationEvent { origin: entry.origin().to_string(), seq: entry.seq(), lamport: entry.lamport(), kind: Some(kind) })
 }