Glissandos: Add a "Minimum length" style setting

OS: Windows 10 (10.0), Arch.: x86_64, MuseScore version (64-bit): 3.5.2.311459983, revision: 465e7b6

One problem that comes up in guitar scores is that adding a straight-line glissando between notes often adds unnecessary extra space as well (e.g. see #310594: Glissandos add too much space between chords).

This could be prevented by adding a "Minimum length" style setting for glissandos. An added glissando would honour the existing inter-note distance as long as it exceeded this minimum.