contracts: Refactor the exec module (#8604)

* contracts: Add default implementation for Executable::occupied_storage()

* contracts: Refactor the exec module

* Let runtime specify the backing type of the call stack

This removes the need for a runtime check of the specified
`MaxDepth`. We can now garantuee that we don't need to
allocate when a new call frame is pushed.

* Fix doc typo

Co-authored-by: Guillaume Thiolliere <gui.thiolliere@gmail.com>

* cargo run --release --features=runtime-benchmarks --manifest-path=bin/node/cli/Cargo.toml -- benchmark --chain=dev --steps=50 --repeat=20 --pallet=pallet_contracts --extrinsic=* --execution=wasm --wasm-execution=compiled --heap-pages=4096 --output=./frame/contracts/src/weights.rs --template=./.maintain/frame-weight-template.hbs

* Review nits

* Fix defect in contract info caching behaviour

* Add more docs

* Fix wording and typos

Co-authored-by: Guillaume Thiolliere <gui.thiolliere@gmail.com>
Co-authored-by: Parity Benchmarking Bot <admin@parity.io>

substrate/bin/node/runtime/src/lib.rs

@@ -782,7 +782,6 @@ parameter_types! {
 	pub RentFraction: Perbill = Perbill::from_rational(1u32, 30 * DAYS);
 	pub const SurchargeReward: Balance = 150 * MILLICENTS;
 	pub const SignedClaimHandicap: u32 = 2;
-	pub const MaxDepth: u32 = 32;
 	pub const MaxValueSize: u32 = 16 * 1024;
 	// The lazy deletion runs inside on_initialize.
 	pub DeletionWeightLimit: Weight = AVERAGE_ON_INITIALIZE_RATIO *
@@ -809,7 +808,7 @@ impl pallet_contracts::Config for Runtime {
 	type DepositPerStorageItem = DepositPerStorageItem;
 	type RentFraction = RentFraction;
 	type SurchargeReward = SurchargeReward;
-	type MaxDepth = MaxDepth;
+	type CallStack = [pallet_contracts::Frame<Self>; 31];
 	type MaxValueSize = MaxValueSize;
 	type WeightPrice = pallet_transaction_payment::Module<Self>;
 	type WeightInfo = pallet_contracts::weights::SubstrateWeight<Self>;