Introduce RPC Worker (#1462)

* Extract json-rpc-client and introduce worker

* Initial rpc worker

* Add error handling

* Use bounded channels for listeners

* Improve naming and clean up

* Use tracing channels

* Improve code readability

* Decrease channel size limit

* Remove unused dependency

* Fix docs

* RPC -> Rpc

* Start worker in initialization method

* Print error in case a distribution channel is full

* Fix docs

* Make `RpcStreamWorker` private

Co-authored-by: Davide Galassi <[email protected]>

* Use tokio channels and add TODO item

* Remove `Option` from `to_worker_channel`

Co-authored-by: Davide Galassi <[email protected]>