Support/use musical font files' x-offset for stems

[Jojo-Schmitz]

Resolves: #25088
Resolves: https://musescore.org/en/node/369769#comment-1261591 where it came up for 3.7. Needs special treatment for Bravura, Emmentaler (particularly bad metadata apparenty), Gonville, Leland, MuseJazz, Petaluma, these fonts' metadata seem to disargee with the stems being offset by half a stem width to the left for upstem notes/chords

[Jojo-Schmitz]

6 fonts (Bravura, Emmentaler, Gonville, Leland, MuseJazz and Petaluma, so basically all but the Finale ones) need some special, and different, treatment. Required quite a bit of fine tuning...

At least for Emmentaler, Gonville, Leland and MuseJazz (the latter 2 don't need special treatment in my MuseScore 3.7) we might be able to instead just fix their metadata.json and there esp. the stemDownNW and stemUpSE values of the affected noteheads, noteheadBlack and noteheadHalf, which would leave just Bravura and Petaluma needing some tweaks. Those might need to get reported upstream (to Steinberg).

Should we ever enable external fonts: the vast majority the ones I tested with (cap1800, Ekmelos, Finale Ash, Finale Engraver, Finale Jazz, Golden Age, Leipzig, Sebastian, Valerio, but not with AloisiusU, AloisiusGrooveU and Legato which has an issue with noteheadDoubleWhole) do work with the defaults. Special mention for Valerio, which actually triggered all this, as it is the only one I came accross so far that does not attach the stems either side of the notes, but basically centers them (for half notes and shorter) to the notehead and without this change here just doesn't look like it should look.

Attached sample scores for all the current fonts Mu4 support:
stem-samples.zip

[Jojo-Schmitz]

Most vtest differences are minor and IMHO harmless and basically an expcted result of ther fine tuning.

These certainly are not:

1. accidental-mirror-1
   
2. arpeggio-2-1
   
3. bravura-10-1
   
4. chord-layout-11-1
   
5. chord-layout-16-1
   
6. chord-layout-21-1
   
7. chord-layout-5-1
   
8. chord-layout-9-1
   
9. chord-layout-dots-2-1
   
10. chord-small-1
    
11. drumset-custom-1-1
    
12. emmentaler-10-1
    
13. fermata-1
    
14. gonville-10-1
    
15. grace-4-1
    
16. layout-sequence-1-1
    
    17; layout-sequence-2-1
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    

[Jojo-Schmitz]

I believe to have found a better way, in my 3.7 PR Jojo-Schmitz#672, by picking on the glyphs notehead_DoubleWhole, noteheadHalf, and noteheadBlack rather than the durations V_LONG, V_HALF and V_QUARTER and fix the metadata for Emmentaler and Gonville's stemUpSE settings for noteheadHalf and noteheadBlack, so only Bravura and Petaluma need special treatment, this should fix most of the issues shown above (leaving just slurs having an issue, as far as I can tell, and I'll try to tackle that). Should fix the other vtest issues and seems to for 3.x.

But I'm now having a hard time porting all this accross to master, without having to use more special treatment and for more fonts. Even the (identical) metadata changes for Emmentaler and Gonville don't work here?!?

Seems I'm missing something that changed in the rendering?
Is my idea of using stemUpSE for the place to attach a stem to entirely flawed?

I'll push what I have rebased and in a 2nd commit (also to check the vtests), please comment.

[Jojo-Schmitz]

It doesn't seem to make any significant difference with the vtests at all!? Issues with small and/or mirrored notes, single note tremolos and all kind of noteheads that this change shouldn't even touch!

Actually I don't really trust those vtests, loading the 'offending' vtest scores into my local build as well as into the artifact show them looking just fine (except for the slurs issue I have with Mu3 too, and on top the single note tremolo issue)!?!