Streaming for deno adapter

[nksaraf]

As per this comment: https://twitter.com/lcasdev/status/1516838233359122434?s=20&t=ufhOOm_SiqHszQPWK0wmHQ, we should be able to stream the static assets from the Deno adapter

      const file = await Deno.open(`.${pathname}`);
      // Respond to the request with the style.css file.
      return new Response(file.readable, {