Batching multi-chain Pact service endpoints

[sirlensalot]

Offer a new set of endpoints for the pact API that are "chain independent" and essentially dispatch to the appropriate apis, since txs self-identify for chains

• send can be unchanged as it's already batch
• local changes so maybe has a different name (locals?)
• poll is batching but might require chain IDs, if so a new name (polls?)
• listen is not indicated for this feature, and offering some kind of join is probably not merited.

[larskuhtz]

Internally, chainweb-node is shared by chain. Each chain has its own pact api. Adding chain independent APIs would change that paradigm and make future physical sharding more difficult.

Even if we add a global ingress in front of the shared pact services, routing would become more difficult, because the proxy would need to parse the request bodies in order to find out to which service to forward to.