Interop: Dependency Manager + New Lockbox Spec

We want to progress the decentralization roadmap at the same time as shipping interop. We also have a bottleneck at multisig operations, it is a lot of overhead for every new upgrade that is put together in [superchain-ops](https://github.com/ethereum-optimism/superchain-ops). We should optimize for reducing the multisig rather than adding to it.

The `SharedLockbox` smart contract was originally designed such that it required multisig operations to update which chains are part of the dependency set and therefore have the ability to withdraw from the `SharedLockbox`. To move away from the multisig operations here, we decided to move the dependency set offchain. This means that an addition to the dependency set can be considered a *hardfork*. On the first block past the hardfork height, the derivation pipeline will create a system tx that calls the `DependencyManager` contract with the new chains added to the dep set which then triggers a withdrawal that authorizes the chain to be able to withdraw from the `SharedLockbox`.

We know that ethereum is "decentralized" and they do upgrades via releases of new software that people opt into running. We should focus on making OP Stack upgrades more similar to that over time. If we can remove the multisig through this mechanism, that would be ideal.

Start with the proposed DependencyManager and SharedLockbox flow, then inspect the referenced superchain-ops repository. The issue names no files, tests, or concrete acceptance condition, so clarify the lockbox spec, dependency-set behavior, and hardfork-triggered system transaction before implementation can be considered done.

Written by the indexing model from the issue text.