Improve video driver selection

Anki is hit with a wave of graphics issue reports with almost every Qt upgrade. Video driver selection support was implemented for Qt6 3 years ago in https://github.com/ankitects/anki/pull/2643. There are probably improvements we can make to detection/fallback logic since then.

Reports (incomplete)

https://forums.ankiweb.net/t/browser-blank-when-card-selected-for-several-seconds/71080