Fix cannot switch between multiple TTS engines

- We didn't reset reset radio button state when user click back
while dialog was popped. Change the UI, when user really accepts the
dialog content, then changes radio button state.
- Migrate TtsEnginePreferenceFragment to RadioButtonPickerFragment

Fixes: 135588938
Test: manual
Change-Id: Ia824e08d59c77a23e6590ff0f5b7d897a73a1ff8