Add Generalized Multicall Capabilities

[bonedaddy]

At the moment I'm using a customized mutlicall contract that exposes view functions for specific functionality. This was due to the complexity of manual abi encoding/decoding with Golang. It is satisfactory, however there is something to be said for having a generalized golang equivalent of multicall.js.

[bonedaddy]

One of the Go-Ethereum devs gave me this code snippet which can be refactored for a Golang equivalent of the Solidity abi.encode function:

// encodeState encodes the state as with abi.encode() in the smart contracts.
func encodeState(state *adjudicator.ChannelState) ([]byte, error) {
    args := abi.Arguments{
        {Type: abiBytes32},
        {Type: abiUint64},
        {Type: abiBytes},
        {Type: abiBytes},
        {Type: abiBool},
    }
    alloc, err := encodeAllocation(&state.Outcome)
    if err != nil {
        return nil, err
    }
    enc, err := args.Pack(
        state.ChannelID,
        state.Version,
        alloc,
        state.AppData,
        state.IsFinal,
    )
    return enc, errors.WithStack(err)
}