Support for compressed MusicXML files.

https://github.com/CoderLine/alphaTab/discussions/1435

https://www.w3.org/2021/06/musicxml40/tutorial/compressed-mxl-files/

1. Read the zip
2. Read the META-INF/container.xml 
3. Find the root file of type application/vnd.recordare.musicxml+xml
4. Read the uncompressed musicXML. 