Better TTS with autoplay

- Adds "still_streaming" to shared module for extensions to know if generation is complete
- Changed TTS extension with new options:
   - Show text under the audio widget
   - Automatically play the audio once text generation finishes
   - manage the generated wav files (only keep files for finished generations, optional max file limit)
   - [wip] ability to change voice pitch and speed
- added 'tensorboard' to requirements, since python sent "tensorboard not found" errors after a fresh installation.

extensions/silero_tts/requirements.txt

@@ -4,3 +4,4 @@ pydub
 PyYAML
 torch
 torchaudio
+simpleaudio