Polish AudioToAudioTranslateProvider which throws if no STT provider is available

Right now the AudioToAudioTranslateProvider class is registered as a taskprocessing provider no matter what.
Inside this class, we throw in

• getOptionalInputShape
• getOptionalInputShapeEnumValues
• getOptionalInputShapeDefaults

if no STT (core:text2speech) provider is found (because audio translation depends on STT).

This produces a lot of level 3 logs.

We could improve this by either:

• Finding a way to only register AudioToAudioTranslateProvider if STT (and the other task types we depend on) are found. Not sure it's possible to check this in the Application::register context.
• Find a way to silently fail, meaning the taskprocessing manager would not produce some logs in this case.

Start with AudioToAudioTranslateProvider, its getOptionalInputShape methods, and the Application::register context. Trace how taskprocessing providers are registered and how missing STT providers produce level 3 logs. Done means audio translation no longer throws or generates those logs when the required STT provider is unavailable.