Reply with an Encodable type

[svara]

This PR adds the option to reply to a message with an object conforming to Encodable protocol. The library handles the encoding using the JSONEncoder.

Example:

private func onItemSelected(at index: Int) {
    reply(to: Event.display.rawValue,
             with: SelectionMessageData(selectedIndex: index))
}

struct SelectionMessageData: Encodable {
        let selectedIndex:Int
}

The library allows to set custom JSON encoder/decoder. The custom encoder/decoder can be useful when you need to apply specific encoding/decoding strategies.
To set a custom encoder/decoder you set it like:

Strada.config.jsonEncoder = myCustomEncoder
Strada.config.jsonDecoder = myCustomDecoder

[jayohms]

Such a nice improvement 👏

[jayohms]

Really wonderful, this will go a long way to simplify using message data within components 👏