Install SFZs on double-click, like SoundFonts

Since the release of 2.1 with improved SFZ support, a few people have reported a problem where MuseScore does not recognize and open the SFZ format the way it does SF2/SF3:

https://musescore.org/en/node/196241
https://musescore.org/en/node/202281
https://musescore.org/en/node/200776

Either the importSoundfont() function should be extended, or a new importSFZ() written, which would copy (or move? maybe worth reconsidering) not only the specific SFZ file but also its associated sound samples.