Improve playback for rolled chords on percussive instruments

(Duplicate of what I posted in the feature request form)

I made a MuseScore file at https://musescore.org/sites/musescore.org/files/Pitched_Percussion_Roll… that explains the feature request much more clearly than in text. Its tl;dr is that it would be nice to have configurable methods of interpreting the playback for a tremolo on a chord, rather than having to go into the pianoroll editor to fix playback, since playing the whole chord for every note of the tremolo is rarely what the composer intends and it's highly unmusical sounding.

My suggested fix algorithm (explained in further detail in the score) is to divide chords as into even (as possible) pitch classes, then two-note tremolo or arpeggiate between those classes in some manner defined by in the instrument file or staff.

This change would, in my opinion, help with the "smart" reputation we're shooting for for 3.0, since it adds just a touch of how a real percussionist would play those notes.