🚀 Feature Request: generate process.env types

[vicb]

Ref:

• Provide mechanism for autopopulating node.js process.env workerd#3311
• Use TEXT bindings for plain text values in Miniflare #7738

There is a pending PR to populate process.env (first ref above) gated by the compatibility flag nodejs_compat_populate_process_env.

Once this is merged, we should update wrangler types to also generate the types for process.env, i.e.

namespace NodeJS {
  interface ProcessEnv {
    VARIABLE: string;
  }
}

/cc @jasnell