Add JSON RPC Batching

[mikedotexe]

In the JSON RPC spec there's an optional way to batch requests.

https://www.jsonrpc.org/specification#batch

For applications that may need to frequently query from multiple places (like pools in DeFi) one could batch these together into a single request.

Since each item in the array is given a unique id it would be nice if a failure were indicated in the eventual response with the key of that id.

Related: https://stackoverflow.com/questions/70729985/are-batch-json-rpc-requests-not-supported-with-near

[mikedotexe]

FASTNEAR has managed to implement JSON RPC Batching, might reach out to @evgenykuzyakov for tips. And as I learn more, hopefully I can help in time.

[evgenykuzyakov]

It's only enabled for read-rpc. I think nearcore can be upgraded to support batch RPC as well, but it requires extra work