RPC trait methods changed from &mut self to self: Rc<Self> and
return types from Promise<(), Error> to impl Future<Output = Result<...>>.
Updated all Server impls across 6 files: DaemonImpl (rpc.rs),
NotifyForwarder (channels.rs), and ChannelServerImpl in all channel
crates (irc, telegram, tmux, socat). Local pry! macro replaces
capnp_rpc::pry to match the new impl Future return type.
Warning-clean workspace build.
Co-Authored-By: Proof of Concept <poc@bcachefs.org>
a421c3c9f3