Added GL_AMBIENT, GL_DIFFUSE and GL_SPECULAR enumerants to LightParameter group

[Rytis-Stan]

Looks like the mentioned enumerants were "lost" from the "LightParameter" group in the commit 8794952a2dfe6332e269191b1288995059df30fd. Here is how the "LightParameter" group looked like just before the changes:

        <group name="LightParameter" comment="Deprecated, use the group attributes instead.">
            <enum name="GL_AMBIENT"/>
            <enum name="GL_CONSTANT_ATTENUATION"/>
            <enum name="GL_DIFFUSE"/>
            <enum name="GL_LINEAR_ATTENUATION"/>
            <enum name="GL_POSITION"/>
            <enum name="GL_QUADRATIC_ATTENUATION"/>
            <enum name="GL_SPECULAR"/>
            <enum name="GL_SPOT_CUTOFF"/>
            <enum name="GL_SPOT_DIRECTION"/>
            <enum name="GL_SPOT_EXPONENT"/>
        </group>

Re-adding the missing enumerants.

Related PR: https://github.com/KhronosGroup/OpenGL-Registry/pull/579

[pdaniell-nv]

@Perksey Do you want to review this since https://github.com/KhronosGroup/OpenGL-Registry/commit/8794952a2dfe6332e269191b1288995059df30fd was your change?

[pdaniell-nv]

@oddhack, this is approved to merge.