UI Viewer - Try to run qmlrunner in a separate process

This will prevent the main app to crash and preserve the theming of the project.

Some projects have slight differences in appearance (cropped icons in eosADAS or red slider in AnimationDemo).

The root cause is having different styles for the main UI and the user project. That causes the second QML engine to inherit the styling from the main UI.

Deleting and reinitializing the qmlengines with qmlClearTypeRegistrations() as a workaround causes the app to become unreliable and causes crashes.