Contracts: use compiled rust tests (#2347)

see #2189

This PR does the following:
- Bring the user api functions into a new pallet-contracts-uapi (They
are currently defined in ink!
[here])(https://github.com/paritytech/ink/blob/master/crates/env/src/engine/on_chain/ext.rs)
- Add older api versions and unstable to the user api trait.
- Remove pallet-contracts-primitives and bring the types it defined in
uapi / pallet-contracts
- Add the infrastructure to build fixtures from Rust files and test it
works by replacing `dummy.wat` and `call.wat`
- Move all the doc from wasm/runtime.rs to pallet-contracts-uapi.

This will be done in a follow up:
- convert the rest of the test from .wat to rust
- bring risc-v uapi up to date with wasm
- finalize the uapi host fns, making sure everything is codegen from the
source host fns in pallet-contracts

---------

Co-authored-by: Alexander Theißen <alex.theissen@me.com>

substrate/frame/contracts/src/tests.rs

@@ -30,9 +30,10 @@ use crate::{
 	},
 	exec::{Frame, Key},
 	migration::codegen::LATEST_MIGRATION_VERSION,
+	primitives::CodeUploadReturnValue,
 	storage::DeletionQueueManager,
 	tests::test_utils::{get_contract, get_contract_checked},
-	wasm::{Determinism, ReturnCode as RuntimeReturnCode},
+	wasm::{Determinism, ReturnErrorCode as RuntimeReturnCode},
 	weights::WeightInfo,
 	BalanceOf, Code, CodeHash, CodeInfoOf, CollectEvents, Config, ContractInfo, ContractInfoOf,
 	DebugInfo, DefaultAddressGenerator, DeletionQueueCounter, Error, HoldReason,
@@ -55,7 +56,6 @@ use frame_support::{
 };
 use frame_system::{EventRecord, Phase};
 use pallet_contracts_fixtures::compile_module;
-use pallet_contracts_primitives::CodeUploadReturnValue;
 use pretty_assertions::{assert_eq, assert_ne};
 use sp_core::ByteArray;
 use sp_io::hashing::blake2_256;