Parts are not loaded for uncompressed format if the file path contains unicode characters

[mercuree]

Issue type

Opening/saving issue

Description with steps to reproduce

• This issue only applies to uncompressed mscx format.
• Parts are completely ignored. If new parts are generated, they will overwrite the old ones that failed to load.
• This issue is based on a report from https://musescore.org/en/node/375290
• I could reproduce the issue since at least version 4.0.2

1. Create folder with unicode character in its name, for example file name with en dash mark: Weiss, Sylvius Leopold 1687–1750
2. Create empty score
3. Open parts and click "Open all"
4. Go to File -> Save as
5. Select previously created folder with unicode character
6. Select file type: Uncompressed Musescore folder (experimental) (*.), remove .mscz from the file name.
7. Click save.
8. Close file
9. Open .mscx file
10. No parts were loaded

Supporting files, videos and screenshots

Path with no unicode characters (parts are loaded):

Path contains unicode characters (no parts)

What is the latest version of MuseScore Studio where this issue is present?

MuseScore Studio version (64-bit): 4.5.0-250510404, revision: github-musescore-musescore-8b8d44b

Regression

Yes, this used to work in MuseScore 3.x and now is broken

Operating system

windows 10

Additional context

No response

Checklist

• This report follows the guidelines for reporting bugs and issues
• I have verified that this issue has not been logged before, by searching the issue tracker for similar issues
• I have attached all requested files and information to this report
• I have attempted to identify the root problem as concisely as possible, and have used minimal reproducible examples where possible