Address Lab/CMYK space subtleties within KoColorSpaceMaths

Summary:
In T4488, two problems were identified with regards to Lab and CMYK when using KoColorSpaceMaths:

• Palette loading was broken
• Calculations themselves were broken: KoColorSpaceMaths assumes [0..1] in floating point whereas Lab has [0.100, -128..+127, -128..+127] and CMYK [0..100].

This patch attempts to fix he following:

• Lab:
  • Specialize Lab traits
• CMYK:
  • Specialize CMYK traits

I still need to figure out how to implement the composite ops, as
they will react differently per channel.

Maniphest Tasks: T4488

Differential Revision: https://phabricator.kde.org/D6589