mtmd : add support for Voxtral (#14862)
* mtmd : add support for Voxtral
* clean up
* fix python requirements
* add [BEGIN_AUDIO] token
* also support Devstral conversion
* add docs and tests
* fix regression for ultravox
* minor coding style improvement
* correct project activation fn
* Apply suggestions from code review
Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>
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Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>
