Query contract module

[td202]

Purpose

Closes #399 Depends on https://github.com/Concordium/concordium-rust-sdk/pull/183

Adds support for smart contracts to query the module reference and contract name of smart contract instances.

Changes

• Add contract_module_reference and contract_name host functions to concordium-std.
• Add support for the new functionality in the testing library.
• Add tests for the implementation in the testing library matching the testing in the scheduler.
• Add a factory smart contract example that demonstrates and tests the functionality.

Checklist

• [X] My code follows the style of this project.
• [ ] The code compiles without warnings.
• [X] I have performed a self-review of the changes.
• [X] I have documented my code, in particular the intent of the hard-to-understand areas.
• [X] (If necessary) I have updated the CHANGELOG.

[DOBEN]

The contract name that we return from the query is appended by the init_ phrase (e.g. "init_contract"). Would it be better if we just return the contract part of the name for simplicity?

[td202]

The contract name that we return from the query is appended by the init_ phrase (e.g. "init_contract"). Would it be better if we just return the contract part of the name for simplicity?

I went this way (partly) because [Owned]ContractName includes the init_ prefix, so it seemed sensible to use that. I didn't want to introduce a new type for the prefix-less contract name, as I feel that would be likely to create confusion, and I didn't really want to mess around too much with the representation of these existing types. While the prefix is clearly redundant, I don't think removing it achieves simplicity, and absent a stronger argument, I propose to keep it.

[DOBEN]

It would be great if the factory logs an event when a new contract is added to the factory. This is particularly useful in (e.g. the uniswapV2 protocol) since indexers pick up the new DEXMarket and provide analytics from that point on for the new trading pair.