Add support for legacy gnosis wallets on L2 in scripts

[leomassazza]

We need to add support for legacy gnosis wallets on L2 in scripts. The required tasks to do that are:

• [x] Understand and experiment using Gnosis Safe on L1
• [x] Legacy Gnosis Multisig on L2
• [x] Understand what owner.js does and how it supports EOAs and Gnosis Safe
• [x] Refactor and clean up owner.js so that it is cleaner, and can be extended to support other types of wallets
• [x] Implement the plugin (util) for Legacy Gnosis Multisig
• [ ] Test Legacy Gnosis Multisig on an L2 instance and simulate an owner migration