Draft: Enable haliumqsgcontext

This change allows the shell and apps to use the Halium project's haliumqsgcontext Qt plugin which, in simple terms, allows Qt to sidestep texture uploads through OpenGL and do them directly through a platform abstraction, which this module provides.

Packages are mirrored right now, so it needs proper packaging still, but other than that CI has binaries and it's doing fine in tests right now on the Pixel 3a.