[utils] fixed design tokens colors lighten modifier

[msereniti]

Motivation and Context

Design Tokens – a Figma plugin that we use in design to manage design tokens. It has colors modifiers that a works... in non trivial way. Our first implementation was using different formulas. New formulas does exactly same calculations like Design Tokens plugin.

How has this been tested?

I have checked that values computed now are exactly the same to the computed by design tokens plugin.

Types of changes

• Bug fix (non-breaking change which fixes an issue).
• New feature (non-breaking change which adds functionality).
• Breaking change (fix or feature that would cause existing functionality to not work as expected).
• Nice improve.

Checklist:

• My code follows the code style of this project.
• I have updated the documentation accordingly or it's not required.
• Unit tests are not broken.
• I have added changelog note to corresponding CHANGELOG.md file with planned publish date.
• I have added new unit tests on added of fixed functionality.