Fix MusicXML export of Hairpin on TimeTick with ChordRest in other staff

[shoogle]

Resolves: #27265

@hhpmusic, let me know if this fixes it for you.

This one was tough to find, partly because the example score was so huge, but also because when I deleted staves to make it smaller, the problem would go away.

I'll add a minimal test case before we merge it.

[hhpmusic]

Thank you, this has been almost solved! The only problem is the gradual tempo changes are not offset. Here's an one-bar example. Also, it's strange that the offsets are converted as backward and forward instead of an offset value which is much cleaner.
In this example, the poco rit text should appear halfway in the measure.
poco rit.zip

[hhpmusic]

Also, in the following example, the crescendo line at m97 is duplicated in voice 2, and then there's only one ending, causing the wedge number to be increased. It should be either in the offset mode of voice 1 of the backup section without a duplication in voice 2.
king.zip