Add Style option for visibility of (non-unison) instrument numbers coincidental with unison labels

Your idea

When unison labels are shown for one voice, there should be an option whether or not to show a label for a single instrument in the other voice on the same shared staff.

Problem to be solved

Currently the red instrument numbers are not automatically drawn. By default they should, but we may add an option to turn off labelling for coincidental non-unison instruments in these situations. Also, it should be possible to choose if such a label appears at the same tick as the unison label, or at the first note for that voice.

Prior art

No response

Additional context

Alternatively/additionally, we could consider adding a text object that would be manually added to the shared stave where required - ideally auto-populating with the correct instrument numbers for the voice.

Checklist

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