SearchBar's clearIcon to have ability to always stay visible

**Is your feature request related to a problem? Please describe.**
The simple task of always showing the clearIcon even when no text is input.

**Describe the solution you'd like**
An "alwaysShowClearIcon" boolean prop on the SearchBar component.

**Describe alternatives you've considered**
Using the "right" prop and custom "icon" props.

Start at the SearchBar component and inspect how clearIcon visibility is determined when the input is empty. Add the requested alwaysShowClearIcon option and verify that the clear icon remains visible without text while preserving the existing behavior when the option is not used.

Written by the indexing model from the issue text.