Stop a request started by speak, or every request when no
requestId is given. Does nothing if the request has already finished.
OptionalrequestId: stringWhat the client's TTS engine can do.
Speak request.text on the client's device.
Resolves once the speech finishes.
The
ttsnamespace on a ClientApplet.Sends requests to the Vivi client, which has the TTS engines. Obtained via
clientApplet.tts.