Allow RpcClient users to inject custom "senders" (#10157)

automerge

client/src/lib.rs

@@ -2,13 +2,13 @@
 extern crate serde_derive;
 
 pub mod client_error;
-mod generic_rpc_client_request;
-pub mod mock_rpc_client_request;
+pub mod http_sender;
+pub mod mock_sender;
 pub mod perf_utils;
 pub mod pubsub_client;
 pub mod rpc_client;
-pub mod rpc_client_request;
 pub mod rpc_config;
 pub mod rpc_request;
 pub mod rpc_response;
+pub mod rpc_sender;
 pub mod thin_client;