[_ColorPalette] Restructure Class and remove hardcoded shades of colors

[BiancaMorandi]

ISSUE
_ColorPalette Class lists many colors without having any link between each others:

• e.g. self.primary_10 is a hardcoded color that is 10% of the primary color -> it would be better for this color to be defined in function of self.primary and not to be hardcoded
• a change of colors listed by self.color_list doesn't have any impact on the inputs colors used for this list e.g self.primary , self.secondary etc... and viceversa
• a change of self.primary , self.secondaryetc. doesn't have any impact onself._color_map` and viceversa

UPDATES TO MAKE
This Class should be improved to have dependencies between self.color_list, self._color_map and each single color and between primary colors and derived shades of the same color.

[stephenholleran]

Thanks @BiancaMorandi !