Warp Precompile Solidity interface + Example Solidity contract to send and receive a message from Subnet A to Subnet B

[aaronbuchwald]

• Add the Solidity interface for the precompile including the events created by the precompile
• Add an Example Solidity contract that uses the interface to send and receive a message
• Create a mock of the precompile to set up a Foundry or HardHat test of the Example Solidity contract (the example contract should treat the mock as coming from the precompile address)

[minghinmatthewlam]

Warp precompile interface will be defined out in #447

[michaelkaplan13]

The working precompile interface is:

// (c) 2022-2023, Ava Labs, Inc. All rights reserved.
// See the file LICENSE for licensing terms.

// SPDX-License-Identifier: MIT

pragma solidity >=0.8.16;

struct CrossChainMessage {
    bytes32 originChainId;
    bytes32 originSenderAddress;
    bytes32 destinationChainId;
    bytes32 destinationAddress;
    bytes payload;
}

interface WarpMessenger {
    event SendCrossSubnetMessage(
        bytes32 indexed destinationChainId,
        bytes32 indexed destinationAddress,
        bytes32 indexed sender,
        bytes message
    );

    function sendCrossSubnetMessage(
        bytes32 destinationChainId,
        bytes32 destinationAddress,
        bytes calldata payload
    ) external;

    function verifySubnetMessage(uint256 messageIndex)
        external
        returns (CrossChainMessage calldata message, bool success);

    function getBlockchainId() external view returns (bytes32);
}