fix(a11y): improve screen reader support for select and array widgets

[Wagner3UB]

Fixes #5139
Partially fixes #5140 (not done - Verify that all chips in large multi-select lists are reachable via keyboard in all edge cases)

What

Improves keyboard and screen reader accessibility for SelectWidget and ArrayWidget (react-select based fields), specifically addressing the Date and Time control panel.

Changes

issue #5139

• SelectWidget: replaced aria-labelledby with a dynamic aria-label that includes the field title and current selected value(s). Falls back to "No value" (translated) when the field is empty. Separated inputId from id so the HTML label correctly points to the react-select inner input.
• ArrayWidget: same aria-label pattern applied for multi-select fields.

issue #5140

• SelectWidget / ArrayWidget: isClearable now respects the required prop — the clear button is hidden on required fields.
• SelectStyling — MultiValueContainer: restored only ref from innerProps on the Popup trigger div to preserve Semantic UI Popup positioning without reintroducing event handler conflicts.
• SelectStyling — SortableMultiValue: added aria-label with field name prefix per chip (using a dedicated fieldTitle prop to avoid fragile string parsing), tabIndex={-1} to remove chips from Tab order (navigation via arrow keys, as announced natively by react-select), and onKeyDown handler to remove a chip via Delete/Backspace/Enter.
• SelectStyling — MultiValueRemove: added role="button" and tabIndex={-1} to mark the remove button as an interactive element.

Behavior after fix

• Screen reader announces field name + current value(s) on focus (e.g. "Available timezones: Europe/Berlin, UTC")
• Empty fields announce "Available timezones: No value"
• Arrow left navigates to chips; react-select natively announces "press left to focus selected values"
• Delete/Backspace/Enter removes the focused chip
• Required fields ("Portal default timezone", "First weekday") no longer show the clear button

[stevepiercy]

Grammar on news. Otherwise LGTM. Needs a technical review. Thank you!

[Wagner3UB]

I put this one in draft because there are too many Cypress test errors to open it.

[Wagner3UB]

This PR has been split into smaller, focused pull requests for easier review and to isolate potential issues:

• fix(a11y): announce field name and current value in select widgets via screen reader #8314 — Announce field name and current value in select widgets via screen reader (aria-label)
• fix(a11y): hide clear button on required select and array widgets #8315 — Hide clear button on required select and array widgets
• fix(a11y): improve screen reader announcements for multi-value chips in select widgets #8316 — Improve screen reader announcements for multi-value chips

Closing this PR in favor of the above.