Companion for Substrate#10568 - Add new BEEFY RPC (#4638)

* support best Beefy RPC through arc<mutex>

* beefy RPC through lockless message passing - wip

Not working because channel can't be simply opened and receiver passed
to `rpc_extensions_builder` because `rpc_extensions_builder` has to be
`Fn` and not `FnOnce`... and and Receiver side of mpsc can't be cloned

yay!..

* beefy RPC through lockless message passing

* beefy: use specialized type definitions

* bubble up service errors from BEEFY RPC

* update lockfile for substrate

Co-authored-by: parity-processbot <>