Remove role="textbox" from search input, per a11y practices. #941

[mlinnetz]

Description

A typical Choices dropdown will add the attribute role="textbox" to the search textbox:
<input type="search" class="choices__input" role="textbox" >

According to a11y best practice, it's recommended to not add the role="textbox" to an text or search element . Rather, screen readers and other assistive technologies already infer that it's a textbox from the element itself.

https://www.w3.org/TR/wai-aria-1.2/#textbox

The intended use is for languages that do not have a text input element, or cases in which an element with different semantics is repurposed as a text field.

https://developer.mozilla.org/en-US/docs/Web/Accessibility/ARIA/Roles/textbox_role

The textbox role is used to identify an element that allows the input of free-form text. Whenever possible, rather than using this role, use an element with type="text", for single-line input, or a <textarea> element for multi-line input.

In other words, both sources imply this should only be used on non-input elements.

Types of changes

• Chore (tooling change or documentation change)
• Refactor (non-breaking change which maintains existing functionality)
• [X ] Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

This PR removes setting a role="textbox" to the input type="search" element of a choices dropdown.

Checklist

• My code follows the code style of this project.
• I have added new tests for the bug I fixed/the new feature I added.
• I have modified existing tests for the bug I fixed/the new feature I added.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[Xon]

LGTM