refactor: superchain address registry

[mds1]

Now, the only thing MultisigTask needs to know about an address registry is its address, so it can be filtered out in the _isValidAction method

• Renames AddressRegistry to SuperchainAddressRegistry
• Deduplicates the two corresponding test files into a single test file
• Cleaner addresses.toml format, and key names now match the network short names
• Removes unused functions from SuperchainAddressRegistry
• Simplifies code and data structures in SuperchainAddressRegistry
• Organizes functions in SuperchainAddressRegistry

cc @blmalone @AmadiMichael @ElliotFriedman @prat-gpt

[blmalone]

Looks good to me.