feat: Add L1 SetGasLimitBuilder abstract script

[BrianBland]

Adds new SetGasLimitBuilder abstract script which simplifies the repeated task of calling the setGasLimit L1 system config method via a gnosis multisig.

To use this, a child class must implement the following 3 virtual function:

function _fromGasLimit() internal virtual view returns (uint64);
function _toGasLimit() internal virtual view returns (uint64);
function _nonceOffset() internal virtual view returns (uint64);

It's expected that the nonce offset will typically be set to 0 for upgrades or 1 for pre-signed rollbacks, while the from and to gas limits may be reversed. It's also possible to use this to pre-sign a number of sequential upgrades and/or rollbacks.

See base/contract-deployments@main...example-gas-limit-upgrade for an example of this new contract in action.

[cb-heimdall]

✅ Heimdall Review Status

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[mdehoog]

nice