some type question

[SteveSuv]

I use colyseus as server of cocos creator project.
but I found some type question:

• ToJSON in @colyseus/schema has no export
• execute in @colyseus/command, it's params payload has no auto type

[endel]

Hi @SteveSuv, thanks for the feedback, could you create a PR for these, please? 🙏 Cheers!