Add a saturation slider underneath the color picker

[Eauix]

Ever since the color sliders were replaced by a 2D color picker, we can no longer adjust the saturation of the colors we choose. If we click anywhere on the picker, we'll get a color with its maximum saturation, and if we want to pick a gray color or a less vibrant tone, we need to directly change the RGB numbers or paste a color copied from an external source.

2 of the 3 sliders' functions were combined into the 2D picker, which is good, but the 3rd slider's function was lost, so what i'm proposing is bringing back this 3rd slider to work alongside the 2D picker

Here's the setup we had before compared to the one we could have after this