The first phase is for the environment before the OS
apps are created, and the second phase is for after
the OS app is created but before all of our processing.
Fixes https://gitlab.com/kicad/code/kicad/issues/7992
wxWidgets seems to cause GTK to spam messages to the terminal,
and we have no control over that. So lets hide the messages
so no one complains about them. If people really want to see
them, they can add the KICAD_SHOW_GTK_MESSAGES build flag to CMake
and they can watch them scroll past.