Add GLES 3.0 and 3.1 functions to QOpenGLFunctions

QOpenGLFunctions it the one true cross-platform GL function wrapper. Unfortunately it is GLES 2.0 only at the moment. Today it is not uncommon to have GLES 3.0 and even 3.1 implementations, especially on mobile, and so some cross-platform solution must be provided that works both with ES3/3.1 and OpenGL 3.x/4.x, as long as the functions in question are available. (ARB_ESn_compatibility is not an option since we need as wide support as possible, including GL 3.x HW/drivers without such extensions)

All the resolving logic is already in place in 5.5 since we do this already for functions like glBlitFramebuffer. All we need to do is to generate the functions, function pointers, resolver functions, etc. for the new stuff in 3.0 and 3.1.

(we may want to put the 3.0/3.1 stuff into a new subclass, though)