Convert to std futures (#58)

* WIP

* Begin converting rpc layer to use std futures and jsonrpsee

* Convert metadata to async/await

* Convert block_hash to async/await

* Convert more methods to async/await

* Remove sp_rpc

* Fix more compilation errors

* Remove connect

* Starting to convert subscription functions

* Use jsonrpsee branch from PR for public client types

* Implement subscribe events with jsonrpsee subscription

* Converting subscriptions and wait_for_block_events

* WIP converting lib methods to async

* Use shared client reference directly for rpc call

`rpc_api!` macro currently only supports RawClient (which cannot be shared).
Also supports named params only which is not currently compatible with substrate rpd which accepts only positional params.

* Use &self instead of &mut self for shared Client

* Convert submit_and_watch to async/await

* Convert more Client fns to async

* Pin some trait futures

* Add serde error

* Fix client creation

* Fix client request compiler errors

* Unify metadata errors

* Add WS handshake error variant

* Fix some more compiler errors

* Fix more compiler errors

* Convert submit_extrinsic to async

* Convert submit and submit_and_watch

* Add Send + Sync constraints

* Clone clients

* Fix EventArg conversion error

* Fix remaining warnings/errors

* Replace deny warnings with specific lints

* Infallable subscription loops

* Use jsonrpsee wss branch

* Fix example

* Start to fix up tests

* Make contracts tests compile

* Make some more tests pass

* Fix up remaining tests

* Fmt

* Use correct event storage key type

* Fix finding events

* Use master jsonrpsee

src/error.rs

@@ -14,7 +14,10 @@
 // You should have received a copy of the GNU General Public License
 // along with substrate-subxt.  If not, see <http://www.gnu.org/licenses/>.
 
-use jsonrpc_core_client::RpcError;
+use jsonrpsee::{
+    client::RequestError,
+    ws::WsNewDnsError,
+};
 use sp_core::crypto::SecretStringError;
 use sp_runtime::transaction_validity::TransactionValidityError;
 
@@ -34,7 +37,13 @@ pub enum Error {
     Codec(#[from] codec::Error),
     /// Rpc error.
     #[error("Rpc error: {0}")]
-    Rpc(RpcError),
+    Rpc(#[from] RequestError),
+    /// Error that can happen during the initial websocket handshake
+    #[error("Rpc error: {0}")]
+    WsHandshake(#[from] WsNewDnsError),
+    /// Serde serialization error
+    #[error("Serde json error: {0}")]
+    Serialization(#[from] serde_json::error::Error),
     /// Secret string error.
     #[error("Secret String Error")]
     SecretString(SecretStringError),
@@ -52,12 +61,6 @@ pub enum Error {
     Other(String),
 }
 
-impl From<RpcError> for Error {
-    fn from(error: RpcError) -> Self {
-        Error::Rpc(error)
-    }
-}
-
 impl From<SecretStringError> for Error {
     fn from(error: SecretStringError) -> Self {
         Error::SecretString(error)