Add a way to listen to multiple protocols on the same endpoint.

[rklaehn]

Basic code to try to deserialize to multiple handlers.

Note that this is very WIP, and also the normal listen fn needs some love if we want to deploy this in prod.

This solves a problem I also had with blobs. Basically much of the RPC api is just available directly on the store, but there are some things that also require an endpoint. So what to do? Always require an endpoint, that sucks for cases where you just want to work with the local store.

Now we can make the "swarm" API and the store api 2 different ones yet handle them both.

I have postponed thinking about this since remote rpc is currently not a priority, but it is very cool.