dev: add to tests end-to-end a new solidity contract: keccak for testing keccak step/builtin consumption

[Elias Tazartes]

Tasks

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1. Update PlainOpcodes.sol contract with the following function and event
2. Add tests in plain_opcodes.py with parametrized input length
3. Identify bottlenecks / breaking points for steps / keccak builtins (for reference, Elias broke the limit on appchain sepolia with 20kb of calldata in RLP)
4. also add the almost same function but without keccak (only abi.encode)
5. If need be, ask Clement/Eni for help for profiling
6. Provide comprehensive profiling runs

Note: you can modify the sol contract to store the hash instead of emitting an event, your choice.

Keccak.sol:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract KeccakTransaction {
    // Event declaration for logging the hash and sender
    event HashComputed(address indexed sender, bytes32 hash);

    // Function to compute and store the keccak256 hash of a given input
    function computeAndStoreHash(string memory input) public {
        bytes32 hash = keccak256(abi.encodePacked(input));
        // Emitting an event with the sender and the hash
        emit HashComputed(msg.sender, hash);
    }
}

[Clément Walter]

See #1071 before