Generic Templating via L2ChainIds

[blmalone]

As discussed on a call with @mds1, @ElliotFriedman, @prateek105, @Ethnical and @blmalone.

We stepped through this forked feature: solidity-labs-io#10

To summarize, in the build function of newly created tasks, we should loop through L2 chain Ids that are imported from a task config .toml file. This way, a task can be reused for many or one chains without having to update any Solidity files. Only the .toml config files would need to be modified.

Similarly, the task may require specific values used in the upgrade e.g. 100_000 for a gas limit update. It's worth thinking about how these can also be parameterized into config instead of having them live in the Solidity file for the same reason as previously mentioned.

[ElliotFriedman]

I'm tackling a lot of the safety scaffolding around the multisig state diff pre and post proposal. Once that is across the line I'm going to investigate this.