seal: Rework contracts API (#6573)

* Transition getter functions to not use scratch buffer

* Remove scratch buffer from ext_get_storage

* Remove scratch buffer from ext_call

* Remove scratch buffer from ext_instantiate

* Add ext_input and remove scratch buffer

* Rework error handling (changes RPC exposed data)

* ext_return passes a flags field instead of a return code
	* Flags is only for seal and not for the caller
	* flags: u32 replaced status_code: u8 in RPC exposed type
* API functions use a unified error type (ReturnCode)
* ext_transfer now traps on error to be consistent with call and instantiate

* Remove the no longer used `Dispatched` event

* Updated inline documentation

* Prevent skipping of copying the output for getter API

* Return gas_consumed from the RPC contracts call interface

* Updated COMPLEXTITY.md

* Rename ext_gas_price to ext_weight_to_fee

* Align comments with spaces

* Removed no longer used `ExecError`

* Remove possible panic in `from_typed_value`

* Use a struct as associated data for SpecialTrap::Return

* Fix nits in COMPLEXITY.md

* Renamed SpecialTrap to TrapReason

* Fix test

* Finish renaming special_trap -> trap_reason

* Remove no longer used get_runtime_storage

* fixup! Remove no longer used get_runtime_storage

* Removed tabs for comment aligment

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

@@ -35,12 +35,15 @@ pub enum ContractExecResult {
 	///
 	/// There is a status code and, optionally, some data returned by the contract.
 	Success {
-		/// Status code returned by the contract.
-		status: u8,
+		/// Flags that the contract passed along on returning to alter its exit behaviour.
+		/// Described in `pallet_contracts::exec::ReturnFlags`.
+		flags: u32,
 		/// Output data returned by the contract.
 		///
 		/// Can be empty.
 		data: Vec<u8>,
+		/// How much gas was consumed by the call.
+		gas_consumed: u64,
 	},
 	/// The contract execution either trapped or returned an error.
 	Error,