Steps to reproduce (assumes ChromeVox or similar)

1. Open https://elastic.github.io/eui/#/forms/color-picker in a new tab.
2. FORCE focus on the color picker element to open it
3. Try and tab around to the different color picker elements: the hue range slider, the hex text input, and the spin element to switch to RGB and other color modes.

Actual Result

The hex text input is the only keyboard accessible portion of the UI

Expected Result

All internal color picker elements should be usable by keyboard

Category: #789: Elastic UI Color Picker Accessibility
Relevant WCAG Criteria: 2.1.1 Keyboard