feat(protocol): add overridable getEIP1559Config() to TaikoL2

[dantaik]

With this new function, we can upgrade the deployment with a derived contract to avoid one SLOAD:

contract CustomTaikoL2 is TaikoL2 {
    function getEIP1559Config() public pure override returns (EIP1559Config memory config) {
        config.xscale = 123;
        config.yscale = 456;
        config.gasIssuedPerSecond = 789;
    }
}

contract ProxiedCustomTaikoL2 is Proxied, CustomTaikoL2 {}

• @davidtaikocha After this PR is merged, please cherry-pick it into alpha-3 branch.

[github-actions]

Overall, this looks like a well-structured pull request. Here are some of the comments that I have:

• The EIP1559Config struct should be documented in the contract documentation.
• The getEIP1559Config() function should be documented in the contract documentation.
• In the eip1559Config() function, it would be better to use the config parameter instead of _param1559. This will make it easier to understand what is being passed as an argument.
• In the _calcBasefee() function, it would be better to use the config parameter instead of individual parameters for xscale, yscale, and gasIssuedPerSecond. This will make it easier to understand what is being passed as an argument.
• In the getBlockHash() function, there should be a brief explanation of what this function does.

[github-actions]

Overall, the code looks good. Here are some suggestions:

• Consider adding a comment at the top of the eip1559Config() function to explain why _param1559 is passed in as an argument.
• Consider adding a comment to explain why you are using uint256 for the basefee variable.
• Consider adding a comment to explain why you are using uint64 for the _xscale and _gasExcess variables.
• Consider adding a comment to explain why you are using uint128 for the _yscale variable.
• Consider renaming the EIP1559Params struct to something more descriptive, like EIP1559Parameters.
• Consider renaming the getEIP1559Config() function to something more descriptive, like getEIP1559Parameters().

[github-actions]

Overall, the code changes look good. Here are some suggestions:

• In the eip1559Config() function, consider renaming the _xscale and _yscale variables to xscale and yscale, respectively, to make them consistent with the other variables in this function.
• Consider adding a comment to the _calcBasefee() function to explain what it does.
• In the same function, consider using more descriptive names for the variables a and b.
• Consider adding a comment in the getEIP1559Config() function to explain why it is a virtual function and why it returns a constant EIP1559Config object.
• In the same function, consider using more descriptive names for the variables config, timeSinceParent, and gasLimit.
• In the generateContractConfigs() file, consider using more descriptive names for the variables param1559 and contractConfigs.