Contracts module rejig (#1358)

* Move prepare under code.

* Schedule update

* CodeHash

* create takes code_hash

* pass mem def and use code in vm::execute

* Actually save and load code

* Use T::Hash as CodeHash

* Explicit entrypoint name

* Return code_hash and deposit an Event

* Charge for deployed code with gas.

* ImportSatisfyCheck and FunctionImplProvider

* Progress.

* Use new infrastructure for checking imports

* Rename entrypoint to entrypoint_name

* Use strings instead of a Error enum

* Clean

* WIP

* Fix macro_define_env test.

* Fix vm code tests.

* Remove tests for now.

* Fix borked merge

* Fix build for wasm

* fmt

* Scaffolding for abstracting vm.

* Hook up execution to exec layer.

* Fix vm tests.

* Use schedule directly in WasmLoader

* Implement test language.

* Add input_data test.

* Max depth test

* ext_caller

* Simplify test.

* Add TODO

* Some tests and todos.

* top_level

* Clean.

* Restore a couple of integration tests.

* Add a few comments.

* Add ext_address runtime call.

* Deduplicate caller/self_account

* Add not_exists test.

* Change bool to TransferCause.

* Add address tests.

* Remove output_buf from parameter.

* return from start fn.

* Smart gas meter

* Tracing

* Fix prepare tests.

* Code moving

* Add ExecFeeToken

* Use tokens everywhere.

* Make it compile in no_std.

* Lift all test requirements to TestAuxiliaries

* A minor clean

* First create tests

* Remove unneeded TODO

* Docs.

* Code shuffling

* Rename create → instantiate

* Add test address.

* Code shuffling

* Add base_fee tests.

* rejig the code

* Add some comments

* on_finalise comment

* Move event deposit further

* Update Cargo.lock

* Use crates.io version of pwasm-utils

* Format todo comments

* Fix formatting

* Comments

* EmptyOutputBuf and OutputBuf split.

* Restore code_hash

* Fix node-executor.

* Fix typo

* Fix fmt

* Update srml/contract/src/account_db.rs

Co-Authored-By: pepyakin <[email protected]>

* Update srml/contract/src/lib.rs

Co-Authored-By: pepyakin <[email protected]>

* Line wraps

* Wrapping macros

* Add _ prefix

* Grumbles

* Doc updates.

* Update srml/contract/src/wasm/mod.rs

Co-Authored-By: pepyakin <[email protected]>

* Update srml/contract/src/lib.rs

Co-Authored-By: pepyakin <[email protected]>

* Add comment

* Use saturation to signal overflow

* Add prepare_test! macro

* Require deploy function.

* Add entry point tests

* Add comment.

* Rename code → code_cache to better describe

* Get rid of weird match!

* Recompile binaries

* Add comments

* refuse_instantiate_with_value_below_existential_deposit

* Little fix

* Make test more complete

* Clean

* Add integration test for instantiation

* Rebuild runtime.

* Add some tests.

* Attach an issue to a TODO

* Attach another issue

* Apply suggestions from code review

Co-Authored-By: pepyakin <[email protected]>

* Update srml/contract/src/exec.rs

Co-Authored-By: pepyakin <[email protected]>

* Update srml/contract/src/exec.rs

Co-Authored-By: pepyakin <[email protected]>

* Recompile node_runtime