Feature: #106637 - Implement accessible combobox pattern
See forge#106637
Description
A new ARIA 1.2 compliant combobox web component has been added that replaces the legacy valuepicker select pattern. The implementation follows W3C accessibility guidelines and includes comprehensive keyboard navigation support.
FormEngine elements including EmailElement, InputTextElement, and NumberElement have been updated to use the new combobox component instead of the previous valuepicker implementation. The link browser components have been adapted to use the combobox pattern as well.
Impact
The component provides full keyboard navigation support with Arrow keys, Enter, Tab, and Escape keys. It includes visual selection indicators with checkmarks and a clear button for resetting the input value.