Buzz Roll Tremolos

[Danielku15]

As requested here: #2372

AlphaTab should add support for Buzz Roll tremolos:

• Model: Adjust the tremolo picking effect
• Importers/Exporters:
  • AlphaTex: New Beat Effect
  • Guitar Pro: Not supported
  • Capella: Unclear
  • MusicXML: Unclear, maybe:
    • Via tremolo and smufl set
    • Via other-ornament and smufl set
• Rendering: Where we currently draw tremolos
• Audio: Unclear, skip unless we get some good examples we can simulate with midi.

[Danielku15]

It might be worth exploring a wider tremolo support as part of this issue:

• Deprecate tremoloSpeed
• Add a new tremolo object with the details similar to musicxml
  • marks (like musicXML but also controlling the audio)
  • symbol defining what symbol to draw https://www.w3.org/2021/03/smufl14/tables/tremolos.html

This way one can control the audio and display separately as needed.

These are variants MuseScore treats as buzz-roll:
https://github.com/musescore/MuseScore/blob/cfbe7bb88711f2921ca404cb085b4690c148856b/src/importexport/musicxml/tests/data/testBuzzRoll.xml
https://github.com/musescore/MuseScore/blob/cfbe7bb88711f2921ca404cb085b4690c148856b/src/importexport/musicxml/tests/data/testBuzzRoll2.xml

MuseScore has no audio generation for buzz-rolls.