Rename & update SandboxConfig trait

[pgherveou]

Follow up from #99

I realized that the current design was not working as I wanted. Specifically, when working with parachain and xcm_simulator::TestExt, I need to use the existing externalities, and the custom execute_with to dispatch messages properly.

• The Sandbox is now created inside the macro (renamed create_minimal_sandbox) along with the runtime. The default setup now uses the MinimalSandbox created through the macro, instead of (the now deleted) Sandbox struct.

• The trait SandboxConfig is renamed Sandbox and exposes these two new APIs

  fn execute_with<T>(&mut self, execute: impl FnOnce() -> T) -> T;
  fn dry_run<T>(&mut self, action: impl FnOnce(&mut Self) -> T) -> T;

• fn initialize_storage is removed since this can be done when the Sandbox is created, and can be customized there instead of being part of the trait.

• The api in sandbox/*_api.rs are updated to be traits with blanket implementations for T: Sandbox instead of impl blocks.

These updates let us create custom sandbox environment that have full control over the storage and execution. An example of this, is the MockNetworkSandbox defined in ink! that uses under the hood the xcm simulator to test connected smart contract that need to interact with a Network of chains.

[pgherveou]

@deuszx @pmikolajczyk41 updated the initial fix.

To avoid using the hacky RefCell & thread_local solution, I updated (one more time 😓) how everything is setup.

• The Sandbox is now created inside the macro (renamed create_minimal_sandbox) along with the runtime. So we use MinimalSandbox instead of Sandbox for the default setup.
• The trait SandboxConfig is renamed Sandbox and exposes these two new APIs

  fn execute_with<T>(&mut self, execute: impl FnOnce() -> T) -> T;
  fn dry_run<T>(&mut self, action: impl FnOnce(&mut Self) -> T) -> T;

  initialize_storage is removed since this can be done when the Sandbox is created, and can be customized there instead of being part of the trait.

• The api in sandbox/*_api.rs are updated to be traits with blanket implementations for T: Sandbox instead of impl blocks.

This needs another pass to make sure some doc string are still up to date, but hopefully this address your concern.

[deuszx]

Thanks @pgherveou , I'll review it this week. Also, before I forget, remember to bump minor version of the crate.

[pgherveou]

Thanks @pgherveou , I'll review it this week. Also, before I forget, remember to bump minor version of the crate.

Gentle ping for review 🙏

[pgherveou]

@deuszx you are still blocking this, would be nice if you could remove the "change requested" or delegate your review to someone else?