MNT: Force PyOpenGL to use EGL or GLX as needed

When running under Wayland, PyOpenGL will default to selecting EGL as its backend. This is not always the correct choice, as applications compiled against X11 can be run under Wayland. The current wxWidgets/wxPython packages on conda-forge are compiled against X11, and are compiled to use GLX for GL initialisation. This means that we must force PyOpenGL to use GLX, and not EGL, as its backend.

This MR also contains an adjustment to the wx.agw.aui.framemanager.AuiFloatingFrame class which will hopefully resolve issues with frozen dialog windows when running under the built-in Windows WSL Wayland server.