Defined colour value included in "Generated Colors"

## Description
Would like to include the specific **Key Color** in the **Generated Colors**, as working with brand colors I would want this as part of the color scale.

## Why do you need this feature?
Including the primary color would be ideal as to have a scale based on the initial color.

## Additional context
None

The issue names no files, tests, or entry points; start by locating the Generated Colors and Key Color handling in the repository. Done means the defined Key Color is included in the Generated Colors as part of the resulting color scale.

Written by the indexing model from the issue text.