VPN-6423: Fix TestQmlPath on Qt 6.6.0 and later

[oskirby]

Description

The TestQmlPath test has been failing for me on Qt 6.6.0 and later, and after a bit digging I traced the crash down into the depths of Qt, which was failing at qquickpathview.cpp:68:75 with the expression QGuiApplicationPrivate::platformIntegration() returning a null pointer. This occurs because the app unit tests are invoked as QCoreApplication instead of a QGuiApplication so the platform integration plugins are never initialized, leading to the segmentation fault in the QML engine.

There are two reasonable ways to fix this issue:

1. We move this test case into the QML Tests, which does initialize the Gui and QML engine, or
2. We just convert the app unit tests into a GUI application.

I have gone with option 2 here.

Reference

JIRA issue: VPN-6423

Checklist

• My code follows the style guidelines for this project
• I have not added any packages that contain high risk or unknown licenses (GPL, LGPL, MPL, etc. consult with DevOps if in question)
• I have performed a self review of my own code
• I have commented my code PARTICULARLY in hard to understand areas
• I have added thorough tests where needed

[lesleyjanenorton]

🎉