Place cross staff dots correctly

[miiizen]

Resolves: #19057
Dot layout now takes cross staff notes from staves above and below into account.

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[cbjeukendrup]

It looks like some parentheses are missing here; adding 1 * VOICES to something that is a staff index seems not a logical thing to do.

Suggested change

	for (size_t i = c->vStaffIdx() + 1 * VOICES; i < c->vStaffIdx() + 2 * VOICES; ++i) {
	for (size_t i = (c->vStaffIdx() + 1) * VOICES; i < (c->vStaffIdx() + 2) * VOICES; ++i) {

But: why would you look at the staff below the "visual staff" of the item in question? Note that cross-staff notation can be created not only by moving notes to the staff below, but also by moving to the staff above. And both can happen simultaneously in the case of a three-staff instrument:

(Or perhaps I'm misunderstanding it completely; excuse me in that case)

[miiizen]

The chord passed into getNoteListForDots is the top chord (lowest track number) on the stave, even if that top chord has been moved down from the stave above, so we can tell if that chord is cross staff easily. This loop is to check through all the voices on the staff below the one we are laying out to see if any voices have been moved up.

[miiizen]

Although, when doing some performance testing I realised this wasn't confined to the current part. It is now.

[miiizen]

Results of some performance testing.

Beethoven 9:
MASTER average: 17136.7288ms
PR average: 17107.996ms

A score of ~2500 bars of cross staff dotted notes:

MASTER average: 765.211ms
PR average: 762.2924ms

Doesn't look like there's too much change compared to master, especially after the last improvement.