Add support for Visual Studio 2026 slnx importing.

[IOBYTE]

No description provided.

[firewave]

Hi @IOBYTE. Great to still see you involved.

This is tracked in https://trac.cppcheck.net/ticket/13721.

Still some things to do:

• add some (Python) tests
• add the file extension in some places in gui/mainwindows.cpp and projectfiledialog.cpp
• add it to the (--project) documentation in lib/cmdlineparser.cpp and manual.md

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[firewave]

The failure can be fixed by adjusting the lines in the suppressions.

I do not think we need to duplicate the whole checks. As the underlying .vcxproj files should be the same it should be enough to add an extra .slnx file to the existing test which contains the same files and just run all the tests with an .slnx input instead (should possibly be done via a pytest parameter).