[mimictts] Fix ssml and playing from audiosinks using the audio servlet (#14120)

[mimictts] Fix ssml and playing from audiosinks using the audio servlet (#14120)

* [mimictts] Fix ssml and playing from an audiosink using the audio servlet

Fix :
- ssml not working
- add an option to store the audio on a file before sending it to openhab. It enables audiosink based on the audio servlet to play the sound (the servlet requires the getClonedStream method, unavailable with a pure streaming approach). The files are stored in the user data directory and deleted as soon as possible (stream close detection).
- fix error with voice name not encoded

Signed-off-by: Gwendal Roulleau <gwendal.roulleau@gmail.com>