Adding Transcription to Convert Functionality for Offline and Online

[kneekey23]

Description of changes:
Transcription added under convert as an api call to both online and offline services supported by CoreML and AWS. In addition to a refactor in order for convert to take advantage of multiservice functionality that will change customer code upon receiving ConvertResult.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[royjit]

Shouldnt this be weak?

[kneekey23]

can't be weak per the protocol from AWSTranscribeStreamingWebSocketProvider and I am not holding a reference to this delegate property from this class on any other class. I am instantiating a new class below that inherits from this protocol so I don't think it has to be weak in this case?

[royjit]

• Still have concerns regarding concurrent requests.
  We create a websocket connection per request, but we donot keep track of it. NativeWebSocketProvider overrides each websocket tasks at line 31. I guess we need to keep track of each websocket connection so that, we can send the right endFrame messages to the right socket.

• I have merged in another PR for the copyright files. You can rebase from master so that we can get rid of all the copyright year files.

[royjit]

• Still have concerns regarding concurrent requests.
  We create a websocket connection per request, but we donot keep track of it. NativeWebSocketProvider overrides each websocket tasks at line 31. I guess we need to keep track of each websocket connection so that, we can send the right endFrame messages to the right socket.
• I have merged in another PR for the copyright files. You can rebase from master so that we can get rid of all the copyright year files.

Decided to have convert() api for transcribe to have one request at a time and it doesnot support concurrent convert operation. So internally the streaming works as request/response model for now.