LibAccelGfx: Use wrapping functions with error check for OpenGL calls

This change introduces GL.h with error check wrappers for all the
OpenGL functions we used so far.

For now, the error check is simply:
`VERIFY(glGetError() == GL_NO_ERROR);`
but that is better than continuing execution after encounting an error.

Userland/Libraries/LibAccelGfx/CMakeLists.txt

@@ -2,6 +2,7 @@ include(accelerated_graphics)
 
 if (HAS_ACCELERATED_GRAPHICS)
     set(SOURCES
+        GL.cpp
         Canvas.cpp
         Context.cpp
         Painter.cpp