add client/server message schemas view

[beiryu]

Displaying schemas is a necessary feature to allow clients (game clients) to know which properties they will use in the schema to make requests and receive corresponding responses.

[endel]

Hi @beiryu, thanks for the PR - I love the idea of presenting how the structures of each message type should look like. I see you have a custom message type for this ("collect_message_schemas"), but how does it look like?

It would be really great if we could use the types of each message and display it in the front-end, I'm afraid that's not easily possible as TypeScript do not expose its types to the runtime.

The upcoming version 0.16 is going to remove the ability to send schema-encoded messages (colyseus/colyseus#745) - Reasoning is: sending schema-encoded messages was only introduced because the C#/Unity SDK lacked a good way to define strongly-typed messages back then. Since we've changed the MessagePack library to use msgpack-unity3d it became possible to define raw message pack types in C#/Unity.

Currently, the playground module extends the original Room code via "monkey-patching" in order to send the __playground_message_types containing message names. If there's more data required to be sent for the clients, that could be a good place to add them...

Cheers!