Fixes hang waiting for cancelled TextToSpeech

[borigas]

Description of Change

There's a bug in Android TTS that if you cancel quickly after starting TTS, SpeakAsync will never return. This is because the CancellationToken was cancelled before the TaskCompletionSource was being assigned, so awaiting the TaskCompletionSource would wait forever. To fix, I moved the creation of the TaskCompletionSource before we register with the CancellationToken

Bugs Fixed

• Fixes [Bug] Android TextToSpeech.SpeakAsync() hangs if cancelled immediately #1894

Provide links to issues here. Ensure that a GitHub issue was created for your feature or bug fix before sending PR.

API Changes

None

Behavioral Changes

Describe any non-bug related behavioral changes that may change how users app behaves when upgrading to this version of the codebase.

PR Checklist

• Has tests (if omitted, state reason in description)
• Has samples (if omitted, state reason in description)
• Rebased on top of main at time of PR
• Changes adhere to coding standard
• Updated documentation (see walkthrough)

[borigas]

I don't think build failures were related to my changes. Let me know if I'm wrong