Add streaming response support

[bnusunny]

This PR adds support for Lambda Streaming Response. I switched the response compression to tow_http::compression::CompressionLayer, because it supports the streaming body.

Issue #, if available:

close #203

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[metaskills]

First, thanks a ton for this work. I just did my first test with LWA in front of an Express server and it worked amazingly well.

I have a question is there an explicit interface to this or does it naturally work with any backend? For example, in an AWS runtime image I would be able to use awslambda.streamifyResponse and do something like this I saw from @aidansteele

    responseStream = awslambda.HttpResponseStream.from(responseStream, metadata);
    responseStream.write("Streaming with Helper \n");
    await new Promise(r => setTimeout(r, 1000));
    responseStream.write("Hello 0 \n");
    await new Promise(r => setTimeout(r, 1000));
    responseStream.write("Hello 1 \n");
    await new Promise(r => setTimeout(r, 1000));
    responseStream.write("Hello 3 \n");
    await new Promise(r => setTimeout(r, 1000));
    responseStream.end();

Is there a way to use the stream within LWA or is it simple getting everything from the proxied web server in a single batch? Hope that makes sense.

[metaskills]

Nevermind, it works juts fine! I did this in Express and it worked amazing well. Y'all are great! I'm used to having to write all this up in the Ruby side.

app.get("/stream", async (_req, res) => {
  res.write("Streaming...\n");
  await new Promise((r) => setTimeout(r, 1000));
  res.write("Hello 0 \n");
  await new Promise((r) => setTimeout(r, 1000));
  res.write("Hello 1 \n");
  await new Promise((r) => setTimeout(r, 1000));
  res.write("Hello 2 \n");
  await new Promise((r) => setTimeout(r, 1000)); 
  res.write("Hello 3 \n");
  res.end();
});