Support for RPC named parameters

[kacper-wolkiewicz-reef]

Hi!
Recently I discovered that chopsticks' RPC API does not accept params as a json object, only an array is accepted:

ERROR (http): Invalid request: {"jsonrpc":"2.0","id":1,"method":"chain_getHeader","params":{}}

This is a violation of JSON RPC 2.0 spec, live chains (or at least Bittensor, which is the one that I tested on) accept the params passed as an object, so I think it would be a good thing to add support for it here too.

[xlc]

What should we do? Auto wrap object params with array?