LibGL+LibSoftGPU: Implement glColorMaterial and GL_COLOR_MATERIAL

When `GL_COLOR_MATERIAL` is enabled, specific material parameters can
be overwritten by the current color per-vertex during the lighting
calculations. Which parameter is controlled by `glColorMaterial`.

Also move the lighting calculations _before_ clipping, because the spec
says so. As a result, we interpolate the resulting vertex color instead
of the input color.

Userland/Libraries/LibSoftGPU/Enums.h

@@ -33,6 +33,20 @@ enum class BlendFactor {
     SrcAlphaSaturate,
 };
 
+enum class ColorMaterialFace {
+    Front,
+    Back,
+    FrontAndBack,
+};
+
+enum class ColorMaterialMode {
+    Ambient,
+    AmbientAndDiffuse,
+    Diffuse,
+    Emissive,
+    Specular,
+};
+
 enum class DepthTestFunction {
     Never,
     Always,