refactor(agents): chain-centric watcher

[lattejed]

Motivation

An operator running a watcher is typically an app owner or L1 partner (chain-centric). In the current, home-centric agent design, they must currently run N watcher instances for each home<>replica channel leading to the chain of interest (high operational burden). A chain-centric watcher would lower that operational burden as well as simplify watcher funding.

Solution

Refactor watcher to watch over all incoming connections to a chain.

PR Checklist

• [ ] Added Tests
• [ ] Updated Documentation
• [ ] Updated CHANGELOG.md for the appropriate package
• [ ] Ran PR in local/dev/staging