* Extract `NetworkKVProvider` trait in `sc-authority-discovery` and remove unnecessary dependency
* Extract `NetworkSyncForkRequest` trait in `sc-finality-grandpa`
* Relax requirements on `SyncOracle` trait, remove extra native methods from `NetworkService` that are already provided by trait impls
* Move `NetworkSigner` trait from `sc-authority-discovery` into `sc-network-common` and de-duplicate methods on `NetworkService`
* Move `NetworkKVProvider` trait from `sc-authority-discovery` into `sc-network-common` and de-duplicate methods on `NetworkService`
* Minimize `sc-authority-discovery` dependency on `sc-network`
* Move `NetworkSyncForkRequest` trait from `sc-finality-grandpa` to `sc-network-common` and de-duplicate methods in `NetworkService`
* Extract `NetworkStatusProvider` trait and de-duplicate methods on `NetworkService`
* Extract `NetworkPeers` trait and de-duplicate methods on `NetworkService`
* Extract `NetworkEventStream` trait and de-duplicate methods on `NetworkService`
* Move more methods from `NetworkService` into `NetworkPeers` trait
* Move `NetworkStateInfo` trait into `sc-network-common`
* Extract `NetworkNotification` trait and de-duplicate methods on `NetworkService`
* Extract `NetworkRequest` trait and de-duplicate methods on `NetworkService`
* Remove `NetworkService::local_peer_id()`, it is already provided by `NetworkStateInfo` impl
* Extract `NetworkTransaction` trait and de-duplicate methods on `NetworkService`
* Extract `NetworkBlock` trait and de-duplicate methods on `NetworkService`
* Remove dependencies on `NetworkService` from most of the methods of `sc-service`
* Address simple review comments
Nazar Mokrynskyi