Enhance V2 Split Contracts Upgradability

[boulder225]

🎯 Problem to be solved

Enhance mutable splits for cluster upgrades and splitter upgrades from fund storage to maximize management during cluster upgrades and enhance fund handling. For updatable clusters, we should figure out how to do immutable ones, edit them, changing the split percentages.

🛠️ Proposed solution

• prototype enhancements for mutable split contracts that support cluster upgrades without compromising predictability.
• Develop a separation of funds that allows the splitter to be upgraded independently from where the funds are stored.