Adding language as an optional argument to HostObject.addTextToSpeech

[JuliaABurch]

Description

Adding language as a parameter to the static helper method HostObject.addTextToSpeech, with a default of en-US -- this is somewhat arbitrary, as the core library actually specifies en-GB as a default language if none is specified. It ultimately checks to make sure the language is supported by the voice, and will select the voice's default language if not.

So this is not a dangerous default to set -- in the sense that if we were to pass in Mizuki (a voice that only supports the language ja-JP) without passing in a language as an argument to override the default, the core library will do the right thing by using ja-JP instead of the en-US default..

Submission Checklist

I confirm that I have...

• [x] removed hard-coded Cognito IDs
• [x] manually smoke-tested the BabylonJS integration tests
• [x] manually smoke-tested the BabylonJS demos
• [x] manually smoke-tested the Three.js integration tests
• [x] manually smoke-tested the Three.js demo

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[eherozhao]

If I remember right, the BabylonJS Editor is only supporting English for now. Will it be a blocker of any of our language support?

[JuliaABurch]

Will it be a blocker of any of our language support?

This does not block any language support. This will allow customers to use this helper method with voices that support more than one language (such as Aditi, which can be used with en-IN or hi-IN.)