Support for OpenGL 3D within Ubuntu host when using Flatpaks

[JeremyP5]

I'm running a application (QGIS) from a flatpak (sandboxed) and it's crashing when calling OpenGL functions. The same application running in the same host works with a standard debian install. See original issue here: https://github.com/flathub/org.qgis.qgis/issues/6#issuecomment-429119399