Enter exact values on sliders

## Description
Add inputs to allow for entering precise values on the lightness, contrast, and saturation sliders.

## Why do you need this feature?
Many workplaces require precision and inputs to enter exact values would be faster and easier than trying to adjust the slider "just right" or using arrow keys to move in 1% increments.

Start by locating the UI controls for the lightness, contrast, and saturation sliders. Add a way to enter precise values for each, then verify that the entered values update the corresponding controls and remain within their supported ranges.

Written by the indexing model from the issue text.