removes use of sc_client::Client from sc-rpc (#5063)

* removes use of sc_client::Client from sc-rpc

* remove Client impl from sc-finality-benches

* remove client impl from sc-finality-grandpa

* read_proof accepts iterator

* remove generic Executor param from ExecutorProvider

* fix long ass line

* code style changes

* merge with master

Co-authored-by: Arkadiy Paronyan <arkady.paronyan@gmail.com>

substrate/client/finality-grandpa/src/observer.rs

@@ -328,7 +328,7 @@ impl<B, BE, C, N> Future for ObserverWork<B, BE, C, N>
 where
 	B: BlockT,
 	BE: Backend<B> + Unpin + 'static,
-	C: crate::ClientForGrandpa<B, BE>+ 'static,
+	C: crate::ClientForGrandpa<B, BE> + 'static,
 	N: NetworkT<B>,
 	NumberFor<B>: BlockNumberOps,
 {