Fix to Line attribute missing in v4

NOTE 6/1/2022: I just posted this issue to the github as that seems to be where MU4 dev issues are being actively managed at this time. See Fix to Line attribute missing in MU4

Started using v4 to try it/ test it. Using the lastest nightly build (MuseScoreNightly-latest-x86_64.AppImage | 2022-05-30). I could not find the 'Fix to Line' attribute in the property inspector for a note.

(I use this fairly often as a work-around for when I need to show only the notes of a melody-line, hiding the other notes in a chord. It is a work-around because when you hide the bottom notes of a chord stack Musescore does not shorten the staff - and in V4 this behaviour has not changed, so I still need the fix-to-line feature.

(I marked it 'major' because it's major to me - tho of course everyone says that. I have no idea how well used this function is - but if it goes missing I assume it will prevent some of my v3.x scores from loading or working in v4.)

(Of course, what I'd personally really like is to fix the stem scaling behavior, per the below post: Reference: Note Stems Not Scaling with Hidden Note Heads)