feat: add stream chat api

[genffy]

issue: https://github.com/prompt-engineering/click-prompt/issues/86

stream api worked not as except, need some help to figure what's wrong.

if config runtime as edge, stream worked, but node:crypto not worked

• add stream like api
• use stream api at ChatRoom
• add SimpleMarkdown to ChatRoom

some refs: https://vercel.com/blog/gpt-3-app-next-js-vercel-edge-functions https://github.com/vercel/next.js/issues/9965#issuecomment-614823642 https://beta.nextjs.org/docs/routing/route-handlers#streaming https://beta.nextjs.org/docs/routing/route-handlers#edge-and-nodejs-runtimes https://nextjs.org/docs/api-routes/edge-api-routes

[genffy]

still WIP, not merge @CGQAQ

[CGQAQ]

👍 LGTM