Allow bagpipe embellishments to be dragged from the score into palettes

Your idea

It should be possible to click-and-drag bagpipe embellishments from the score into palettes.

This would be particularly useful in cases where the score features a customised embellishment (not featured in the current Bagpipe embellishments palette) and you want to save it for reuse later.

Problem to be solved

1. Add a bagpipe embellishment (single grace note or a more complex embellishment) to a note
2. Try to click-and-drag the embellishment into palettes as you would with any other engraving item

https://github.com/user-attachments/assets/a1fab9c1-c47f-4307-ac9a-2dccbf3b93b7

Prior art

No response

Additional context

Some design is probably needed here because, apart from single grace notes, it's unclear how exactly a click-and-drag interaction would work for embellishments consisting of multiple notes.

Originally raised by @fletch2770 in #28702

Checklist

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