Investigate EGL based rendering error / WGL option

[hhyyrylainen]

Starting on Windows there are some missing EGL dll warnings

Maybe the wgl option should be put on to prefer that (with command line flag to disable)?

This is the exception:

[OpenGL] Unable to initialize EGL-based rendering: 'System.DllNotFoundException: Dll was not found.
   at Avalonia.OpenGL.Angle.AngleEglInterface.EGL_GetProcAddress(String proc)
   at Avalonia.OpenGL.Angle.AngleEglInterface.LoadAngle() in /_/src/Avalonia.OpenGL/Angle/AngleEglInterface.cs:line 21
   at Avalonia.OpenGL.Angle.AngleWin32EglDisplay..ctor() in /_/src/Avalonia.OpenGL/Angle/AngleWin32EglDisplay.cs:line 65
   at Avalonia.Win32.Win32GlManager.<>c.<Initialize>b__0_1() in /_/src/Windows/Avalonia.Win32/Win32GlManager.cs:line 25
   at Avalonia.OpenGL.Egl.EglPlatformOpenGlInterface.TryCreate(Func`1 displayFactory) in /_/src/Avalonia.OpenGL/Egl/EglPlatformOpenGlInterface.cs:line 34'