feat: introduce fee splitter for revenue share

[0xDiscotech]

Description

Introduce the FeeSplitter predeploy as part of a new revenue-sharing feature. The goal is to make revenue sharing simpler and more modular, with configurable values and automated handling where possible.

Includes supporting contracts like SuperchainRevSharesCalculator, L1Withdrawer, and FeesDepositor, which act as periphery components of the system and cover the first expected use case.

This is opt-in, but will be enabled by default on fresh chains at genesis. Operators must set a chain fees recipient address on L2 for splits to work.

FeeVaults were updated to be more flexible with setters, while keeping backwards compatibility.

Tests

• All new contracts are fully unit tested.
• Genesis logic has dedicated tests, and there ar integration tests covering the full main flow.
• Invariant tests added using Foundry as fuzzer.

Additional context

• specs
• design-docs

Metadata

When the FeesDepositor contract for OP’s L1 fees is deployed, it should be linked here

⚠️ Disclaimer: We made minimal changes to the Go files to get the checks passing and did so carefully. Go isn’t our primary expertise, so we’d appreciate extra attention from Go reviewers on these edits.

[JosepBove]

As I mentioned on our chats, everything LGTM. Just this minor spec mismatch-related stuff.

[JosepBove]

Thanks for the fixes, approved.