Streaming API: Eleven Labs Models and Gladia Support

We've add support for choosing between Eleven Lab models such as eleven_flash_v2_5 or eleven_multilingual_v2. To see the trade offs either model, see: https://elevenlabs.io/docs/models

We've excited to partner with Gladia: a new speech to text provider, providing strong multi lingual support on speech recognition side.

More details here on how to configure these, see: https://docs.heygen.com/reference/new-session