contracts: Refactor the runtime API in order to simplify node integration

[athei]

Currently, in order for a node to implement the contracts runtime api it is necessary to copy paste some conversion logic:

impl pallet_contracts_rpc_runtime_api::ContractsApi<Block, AccountId, Balance, BlockNumber>
 		for Runtime
{
	fn call(
		origin: AccountId,
		dest: AccountId,
		value: Balance,
		gas_limit: u64,
		input_data: Vec<u8>,
	) -> ContractExecResult {
		let (exec_result, gas_consumed) =
			Contracts::bare_call(origin, dest.into(), value, gas_limit, input_data);
		match exec_result {
			Ok(v) => ContractExecResult::Success {
				flags: v.flags.bits(),
				data: v.data,
				gas_consumed: gas_consumed,
			},
			Err(_) => ContractExecResult::Error,
		}
	}
}

This PR reduces it to:

impl pallet_contracts_rpc_runtime_api::ContractsApi<Block, AccountId, Balance, BlockNumber>
 		for Runtime
{
	fn call(
		origin: AccountId,
		dest: AccountId,
		value: Balance,
		gas_limit: u64,
		input_data: Vec<u8>,
	) -> pallet_contracts_primitives::ContractExecResult {
		Contracts::bare_call(origin, dest, value, gas_limit, input_data)
	}
}

It does this by moving common types to the pallet-contracts-primitives crate and by that removing the need for intermediate types that made those conversions necessary.

I think this is important because this conversion logic is duplicated in every runtime and is also part of a tutorial that can be simplified by doing so (@danforbes @wheresaddie).

Because this modifies a runtime API a client update is necessary. This API is only used by a the contracts_call RPC and is therefore not critical: It is only relevant for public RPC nodes. Nonetheless I bumped the priority to medium to signal that a client update is necessary to restore this RPC functionality.

[bkchr]

Because this modifies a runtime API a client update is necessary. This API is only used by a the contracts_call RPC and is therefore not critical: It is only relevant for public RPC nodes. Nonetheless I bumped the priority to medium to signal that a client update is necessary to restore this RPC functionality.

If the runtime upgrade and the client upgrade are done together, there shouldn't be any problem. Otherwise, there will be always a period of time until both are in sync to make it work again.

[ascjones]

LGTM

[NikVolf]

Other than some minor formatting grumbles, looks great!

[athei]

bot merge

[ghost]

Waiting for commit status.

[wheresaddie]

👍

[ghost]

Checks failed; merge aborted.

[athei]

bot merge

[ghost]

Waiting for commit status.