Revise Qt Quick 3D CustomMaterial and Effect

Currently, the shaders accepted by CustomMaterial and Effect is still quite old-styled as far as I see it. I would say what QQEM uses is more modern, standard and powerful. Some key features being requested by users: storage buffer and uniform buffer.

And there are actual use cases too: some users need the low-level shading capability of Qt 3D, but also need the RHI capability of Quick 3D (another reason is that Qt 3D is deprecated). But writing entire pipeline using QRhi* is too low-level.