feat(text-to-speech): add support for using synthesize

[dpopp07]

Adds a new method - synthesizeUsingWebSocket - that returns a ReadableStream that the user can pipe into a new file or over the speakers. Returning a stream seemed to be the best user experience since the point of websocket is to allow the user to receive data in chunks in real time without reading all data into memory at once.

I tried to keep the design similar to recognizeUsingWebSocket for a consistent experience, but did not adopt any code that seemed unnecessary.

There might be more features that are needed but this provides the basic needs of the user with simple code and a simple interface.

I still need to write tests and an example but wanted to start getting feedback on the implementation.

cc @ehdsouza @jsstylos @jeffpk62

Todo:

• Write tests
• Write an example

---

This is what the experience looks like for the user:

const tts = new TTS({
  username,
  password,
});

const params = {
  text: 'Hello world.',
  accept: 'audio/ogg;codecs=opus',
};

// create the stream
const synthStream = tts.synthesizeUsingWebSocket(params);

// pipe the stream into a new audio file
synthStream.pipe(fs.createWriteStream('./speech.ogg'));

// optionally, the user can listen to data as it is returned from the service
synthStream.on('message', (message, data) => {
  console.log(data);
});

[germanattanasio]

How can you see when the websocket was closed? can we have an on('close')?

[dpopp07]

There is a close event emitted when the connection closes, on Line 124 of synthesize-stream.ts.

self.emit('close', event.code, event.reason);

I just didn't include it in the demo.

[codecov-io]

Codecov Report

Merging #807 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #807   +/-   ##
=======================================
  Coverage   95.65%   95.65%           
=======================================
  Files           2        2           
  Lines          46       46           
  Branches        2        2           
=======================================
  Hits           44       44           
  Misses          2        2

---

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[dpopp07]

@germanattanasio documentation, example, and test added

[germanattanasio]

Nice 🎉

[germanattanasio]

When running in node we use the ws package but do we create a bundle for the browser without it? and is the ws interface the same as the WebSocket interface in a browser?

The questions are not related to this PR which is good

[germanattanasio]

👍 Good job @dpopp07