Move srml RPC extensions to separate crates (#3791)

* Move srml-system RPC out.

* Fix tests for system-rpc module.

* Contracts RPC moved.

* Fix rpc test.

* Clean up.

* Update lockfile.

* Bump runtime version.

* Update srml/contracts/rpc/runtime-api/src/lib.rs

Co-Authored-By: Bastian Köcher <bkchr@users.noreply.github.com>

* Bump impl version.

substrate/srml/contracts/rpc/runtime-api/src/lib.rs

@@ -0,0 +1,64 @@
+// Copyright 2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Runtime API definition required by Contracts RPC extensions.
+//!
+//! This API should be imported and implemented by the runtime,
+//! of a node that wants to use the custom RPC extension
+//! adding Contracts access methods.
+
+#![cfg_attr(not(feature = "std"), no_std)]
+
+use rstd::vec::Vec;
+use codec::{Encode, Decode, Codec};
+
+/// A result of execution of a contract.
+#[derive(Eq, PartialEq, Encode, Decode)]
+#[cfg_attr(feature = "std", derive(Debug, serde::Serialize, serde::Deserialize))]
+pub enum ContractExecResult {
+	/// The contract returned successfully.
+	///
+	/// There is a status code and, optionally, some data returned by the contract.
+	Success {
+		/// Status code returned by the contract.
+		status: u8,
+		/// Output data returned by the contract.
+		///
+		/// Can be empty.
+		data: Vec<u8>,
+	},
+	/// The contract execution either trapped or returned an error.
+	Error,
+}
+
+client::decl_runtime_apis! {
+	/// The API to interact with contracts without using executive.
+	pub trait ContractsApi<AccountId, Balance> where
+		AccountId: Codec,
+		Balance: Codec,
+	{
+		/// Perform a call from a specified account to a given contract.
+		///
+		/// See the contracts' `call` dispatchable function for more details.
+		fn call(
+			origin: AccountId,
+			dest: AccountId,
+			value: Balance,
+			gas_limit: u64,
+			input_data: Vec<u8>,
+		) -> ContractExecResult;
+	}
+}