Identify reusable code for speech-synthesis feature.

[pixelzoom]

number-pairs is currently not reusing anything from number-suite-common. And we probably need to keep it that way for now, due to PhET-iO support issues. But there is a lot of existing code related to the speech-synthesis feature that we should inspect, especially since the design is the same for number-pairs. Some code we might consider generalizing, adding PhET-iO support, and moving to common code. Other code we might be able to copy and improve.

Here's the existing code that's related to the speech synthesis feature. (This might not be a complete list.)

number-suite-common:

• LanguageAndVoiceControl - 2 carousels that replace the standard UI in Preferences > Localization
• SecondLanguageControl - ABSwitch and 1 carousel that typically appears in Preferences > Simulation
• SpeechSynthesisButton
• NoVoiceWarningButton
• NoVoiceWarningDialog

number-play:

• LocaleSwitch - ABSwitch between primary and secondary locale
• numberPlaySpeechSynthesisAnnouncer
• numberPlayUtteranceQueue

number-compare:

• numberCompareSpeechSynthesisAnnouncer
• numberCompareUtteranceQueue

[pixelzoom]

LanguageAndVoiceControl and SecondLanguageControl were components that I thought would be good candiates to move to joist. But looking at their current implementations, they are tightly coupled to UtteranceQueue in general, and the NumberSuiteCommonUtteranceQueue subclass of UtteranceQueue in particular. So the first order of business will be to see if they can be decoupled.