use autoplace for notenames plugin's staff text

[Jojo-Schmitz]

placing voice 2 and 4 below staff, 1 and 2 above, as before, but now using autoplace rather than fixed offsets.

Solves https://musescore.org/en/node/296788 and https://musescore.org/en/node/296916

[Jojo-Schmitz]

Well, I don't see any reason why this would need to wait for 3.4?
I don't see any urgency either though, i.e. no need for it to be in 3.3.1, but also no harm.

[dmitrio95]

Maybe I misunderstood the purpose of this change then:
https://github.com/musescore/MuseScore/pull/5467/files#diff-fb15bc815be1546cdb92f42a00e4a6d8L21-R21

[Jojo-Schmitz]

Ah, yes, indeed, this is just a bump in the plugin's version number, no relation to the MuseScore version it'd run on. Not an important part of that PR at all, just cosmetic. Not anthing like those \since comments in the pulgin API code.
If you want then being in sync, just let me know and also tell which version it'd be merged into.
None of the other plugins' version numbers follow the MuseScore version number though.
@DLLarson might have had that in mind in his 26ab4f5 though