environment variables improvement

[himself65]

treat WAKU_PUBLIC_ prefix as public env vars that can only be used in client side rendering (or ssr?)

others can be used in RSC

[dai-shi]

Implementation-wise, it's a bit complicated as we want to support both Node and non-Node. I'll work on it later.

[himself65]

Cloudflare: https://developers.cloudflare.com/workers/configuration/environment-variables/#add-environment-variables-via-wrangler

Deno: https://examples.deno.land/environment-variables

[dai-shi]

Thanks. So, I'm sure Waku core should simply accept an env object and adapters for Node.js, CFW, and Deno translate to it.

[dai-shi]

I would like to avoid using process.env in the source code, even though they are transpiled. Maybe, __WAKU_ENV__ or something.