Is your feature request related to a problem? Please describe.

For TTS, there is a need to choose a specific model or send additional data to the engine on how to handle a part of the text. Examples:

• rendering a dialog with different voices
• rendering a part with specific emotion (joy, fear, sadness, suprise...)

Describe the solution you'd like
Support SSML / coqui markup in input text. Example:

- <tts model="male_voice_1"> Check the box under the tree </tts>
- <tts model="child_voice_1"> This one?   <tts emotion="joy">Wow, it's the Harry Poter lego!</tts>  </tts:model>