Group jsonrpc batched eth_calls into one multicall internally and decode the output

[carneiro-cw]

When processing an eth_call batch request we could group it and create a multicall from it before passing it along, we'd then need to parse the response back to the jsonrpc batch format.

One thing to note is that this can only work by grouping by the point in time the call will run on.

example request/response format:

curl -sS http://localhost:3000/?app=carneiro \
           -H 'content-type: application/json' \
           --data '[
  {
    "jsonrpc": "2.0",
    "id": 1,
    "method": "eth_call",
    "params": [
      {
        "to": "<contract>",
        "data": "0x18160ddd"
      },
      "latest"
    ]
  },
  {
    "jsonrpc": "2.0",
    "id": 1,
    "method": "eth_call",
    "params": [
      {
        "to": "<contract>",
        "data": "0x18160ddd"
      },
      "latest"
    ]
  },
  {
    "jsonrpc": "2.0",
    "id": 1,
    "method": "eth_call",
    "params": [
      {
        "to": "<contract>",
        "data": "0x18160ddd"
      },
      "latest"
    ]
  },
  {
    "jsonrpc": "2.0",
    "id": 1,
    "method": "eth_call",
    "params": [
      {
        "to": "<contract>",
        "data": "0x18160ddd"
      },
      "latest"
    ]
  },
  {
    "jsonrpc": "2.0",
    "id": 1,
    "method": "eth_call",
    "params": [
      {
        "to": "<contract>",
        "data": "0x18160ddd"
      },
      "latest"
    ]
  }
]
' | jq

response:

[
  {
    "jsonrpc": "2.0",
    "id": 1,
    "result": "0x00000000000000000000000000000000000000000000000000ffffffffffffff"
  },
  {
    "jsonrpc": "2.0",
    "id": 1,
    "result": "0x00000000000000000000000000000000000000000000000000ffffffffffffff"
  },
  {
    "jsonrpc": "2.0",
    "id": 1,
    "result": "0x00000000000000000000000000000000000000000000000000ffffffffffffff"
  },
  {
    "jsonrpc": "2.0",
    "id": 1,
    "result": "0x00000000000000000000000000000000000000000000000000ffffffffffffff"
  },
  {
    "jsonrpc": "2.0",
    "id": 1,
    "result": "0x00000000000000000000000000000000000000000000000000ffffffffffffff"
  }
]

[carneiro-cw]

Alternatively we could have a new endpoint (stratus_batchCall or something), that does this automatically but instead accepts a list of lists of call inputs, but only a fixed point in time (we'd have to instruct ppl to actually use it though).