Strange behavior of WM_ACTIVATEAPP on Win10.

[Andrey Korotkov aka megaDRONe86]

This even could occur before any plugin was inited through EPT_INIT event. In this case it broke stuff for example in D3D9 renderer.
Also there is strange break in code that forwards code execution to the next case in some situations.
https://github.com/DGLE-HQ/DGLE/blob/master/src/engine/platform/windows/MainWindow.cpp#L100

[Andrey Korotkov aka megaDRONe86]

Detailed information on issue: When D3D9 tries to go fullscreen it cause window reinit process in Windows and WM_ACTIVEAPP happens that cause wrong behavior in all engines subsystems.