Support for xaphoon instrument

[eduardomourar]

Implements a feature request: https://musescore.org/en/node/11028

In order to create a new staff with Xaphoon (Pocket sax) instrument, we need to add it to the instruments XML file. This is based in the file from user AirW (found here).

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• I created the test (mtest, vtest, script test) to verify the changes I made

[Jojo-Schmitz]

Sorry, I missed some changes that are IMHO needed to the instrument names (capitals, hyphens, flat sign), see and check #5603