Fix #297482 - Score layout shifts when saved with fingering on acciaccatura

[njvdberg]

…catura

Resolves: https://musescore.org/en/node/297482#comment-984598

Solves the shift of the fingering on the grace note, and therefor the shift of the line above the fingering.

The root cause was StemSlash. Shapes for the StemSlash are created during the layout of the beams of the grace notes and the layout of these beams is with the layout of the complete Chord to which the grace notes belong. As a result, the shapes of StemSlash are added to the skyline after the layout of the Fingering so the layout of the Fingering was based of the layout of the Stem only.
After a re-layout the StemSlash is included in the skyline so the re-layout will move
the Fingering and, in this case, also the line.
The solution was a extra layout of the StemSlash in Score::layoutChords3() so its StemSlash is included in the skyline in time.

Although this issue is very similar to #302316 and fix #297501, the root cause is different.

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[njvdberg]

This PR is related to #5812 but has a different root cause and is therefor independent.