Proof of concept: Add a new runtime that uses pallet_contracts (#186)

* seal: Copy over a legacy version of pallet_contracts from substrate

* seal: Fix substrate dependency pathes and add as dependency to runtime

* seal: Adapt pallet to current substrate version

* seal: Add contracts pallet to runtime

* seal: Implement rpc runtime api

* seal: Update to latest rpc output format

* seal: Replace child trie by prefix trie

* seal: Add contracts endpoint to the client

* seal: fixup rpc test

* Fix whitespace issue

Co-authored-by: Sergei Shulepov <sergei@parity.io>

* seal: Move pallet out of the runtime directory

* seal: Create a seperate runtime for contracts

* Move parachains to top level directory

* seal: Disable rent for easier testing

Co-authored-by: Sergei Shulepov <sergei@parity.io>

rococo-parachains/pallets/contracts/common/src/lib.rs

@@ -0,0 +1,47 @@
+// Copyright 2020 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/>.
+
+//! A crate that hosts a common definitions that are relevant for the pallet-contracts.
+
+#![cfg_attr(not(feature = "std"), no_std)]
+
+use sp_std::prelude::*;
+
+/// A result type of a get storage call.
+pub type GetStorageResult = Result<Option<Vec<u8>>, ContractAccessError>;
+
+/// The possible errors that can happen querying the storage of a contract.
+#[derive(Eq, PartialEq, codec::Encode, codec::Decode, sp_runtime::RuntimeDebug)]
+pub enum ContractAccessError {
+	/// The given address doesn't point to a contract.
+	DoesntExist,
+	/// The specified contract is a tombstone and thus cannot have any storage.
+	IsTombstone,
+}
+
+/// A result type of a `rent_projection` call.
+pub type RentProjectionResult<BlockNumber> =
+	Result<RentProjection<BlockNumber>, ContractAccessError>;
+
+#[derive(Eq, PartialEq, codec::Encode, codec::Decode, sp_runtime::RuntimeDebug)]
+pub enum RentProjection<BlockNumber> {
+	/// Eviction is projected to happen at the specified block number.
+	EvictionAt(BlockNumber),
+	/// No eviction is scheduled.
+	///
+	/// E.g. because the contract accumulated enough funds to offset the rent storage costs.
+	NoEviction,
+}