Fix WinGet malfunction false positives

[Marc-André Moreau (mamoreau-devolutions)]

Summary

• fix false-positive WinGet malfunction state so successful installed-package listing clears the warning condition
• skip broken native WinGet package entries during installed/update enumeration instead of aborting the entire listing
• respect the existing DisableWinGetMalfunctionDetector setting in both WinUI and Avalonia warning logic

Testing

• dotnet build .\src\UniGetUI.sln --nologo -v minimal
• dotnet test .\src\UniGetUI.sln --nologo --no-build -v minimal
• launched WinUI build from src\UniGetUI\bin\x64\Debug\net10.0-windows10.0.26100.0\win-x64\UniGetUI.exe

Closes #4518