feat: implementation of token transfer (ICS20) contract

[Farhad-Shabani]

Closes: #21

Description

We initially planned to write a simple ICS20 contract with basic operations to familiarize ourselves with the essentials. However, as I added more elements, it evolved into a full ICS20 token transfer contract. This first version isn't perfect and might not have the best design choices, but it serves as a solid first iteration. It sets the stage for team discussions and helps us nail down the details as we move forward.

Components

This PR includes the following components. In Cairo contracts, a component is like a reusable building block that can be combined with others to create a smart contract with all the needed features.

• ICS20TransferComponent: Handles ICS20 token transfers.
• TransferrableComponent: Allows the Transfer contract to control sending and receiving tokens.
• ERC20MintableComponent: Adds mintable / burnable features to a regular ERC20 contract, making the total supply flexible for IBC contracts.
• IBCGovernanceComponent: Allows a governance to update specific IBC states, especially for contract upgrades and setting ERC20 class hashes. The current implementation is basic and aims to show how it connects with other components.

Preset Contracts

By using the above components and a few others from the OpenZeppelin repository, two contracts have been implemented:

• ERC20: An extended ERC20 contract with mintable capabilities for a flexible total supply.
• Transfer: The contract for IC20 token transfer.

Unit Tests

The following tests cover the happy path for when a MsgTransfer or recv Packet is submitted to the Transfer contract. Further tests, particularly to catch faulty scenarios, can be added in a subsequent PR.

• test_escrow_unescrow_roundtrip
• test_mint_burn_roundtrip

Scripts

• Contract deployment steps
• Contract invocation steps

CI Job

• Contract tests are included

Highlights

• Verifying ByteArray is quite expensive. We need to find the most efficient way to verify string-like variables. For example, identifiers such as PortId and ChannelId, which are strings in IBC, must be checked to ensure they meet specifications. Deciding on the best approach will finalize the argument types for some contract APIs.

TODO

• Conduct a self-review
• Specify the key computation algorithm
• Update invoke.sh

[soareschen]

I'll merge this first to minimize merge conflicts. we can review it synchronously later.

[soareschen]

I think we can use the hash methods provided by Cairo to hash the byte array? https://book.cairo-lang.org/ch11-04-hash.html

[Farhad-Shabani]

Thanks for pointing this out. I tried it in #38. It perfectly works. Way cheaper than those functions.