Deprecate "confirmed" RpcClient methods (#16520)

* Remove obsolete client methods

* Deprecate GetConfirmed client methods

* Rename Confirmed config structs, with appropriate deprecation

* Fixup client apps

* Map RpcRequest to deprecated when targeting older nodes

client/src/lib.rs

@@ -13,6 +13,7 @@ pub mod rpc_cache;
 pub mod rpc_client;
 pub mod rpc_config;
 pub mod rpc_custom_error;
+pub mod rpc_deprecated_config;
 pub mod rpc_filter;
 pub mod rpc_request;
 pub mod rpc_response;