ENSCacheProvider and NeynarClientProvider are relatively standalone components, and can safely be rendered higher in the tree.
On the other hand, TunnelbrokerProvider now handles notif sending, and as such is tightly coupled with business logic. We should render it lower in the hierarchy.
This diff solves ENG-9641 by making sure the DM notif-sending code in TunnelbrokerProvider is able to access the ENSCache in ENSCacheProvider, and the Farcaster username resolving code in NeynarClientProvider.