Create tuplet bracket when on notehead side

[miiizen]

Resolves: #17852

When a tuplet's bracket type is set to auto, display a bracket if on the notehead side of beamed notes.

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[cbjeukendrup]

I found an edge case that seems not to be covered, namely when all notes of the tuplet are moved to the staff below (or above):

I would expect a bracket for the last tuplet.

Is that indeed an issue, or should we ignore it because there is no good reason to notate it like this?

[cbjeukendrup]

Maybe it would be fixed by changing this to c1->vStaffIdx() != c2->vStaffIdx(). That way, all these cases would be handled the same:

[cbjeukendrup]

The VTests were unwilling, so I've rebased the branch, hoping that will help.