fix(ui5-li): do not set aria-selected on role listitem (#14235) - #14245

PR checklist

• Check the Development Hints
• Follow the Commit message Guidelines
• Add proper description about the background of the change and the change itself
• Link to an existing issue (if available)
• Read the Contributing Guidelines

Background & Description

In ListItem (and derived components like UploadCollectionItem), the root <li> renders with role="listitem" by default. Under the W3C WAI-ARIA specification, aria-selected is strictly permitted only on the following roles: gridcell, option, row, tab, columnheader, rowheader, and treeitem.

Applying aria-selected (e.g. aria-selected="false" or aria-selected="true") to an element with role="listitem" violates WAI-ARIA and triggers automated accessibility failures (e.g. axe-core rule aria-allowed-attr and AccessContinuum test 264).

Selection state for listitem elements is already communicated accessibly via:

1. ariaSelectedText ("Selected" / "Not Selected") announced in aria-describedby
2. Interactive selection controls (ui5-checkbox with aria-checked in Multiple mode, and ui5-radio-button in single selection mode)

When ListItem is configured with role="option" (e.g. in a ListBox container) or role="treeitem", aria-selected is valid and remains properly exposed.

Changes

• In packages/main/src/ListItem.ts: Conditionally expose ariaSelected in _accInfo only when the item's accessible role supports it (option or treeitem), preventing invalid aria-selected attributes from rendering on role="listitem".
• Added Cypress integration tests in packages/main/cypress/specs/List.cy.tsx validating that:
  • Items with role="listitem" do not render aria-selected.
  • Items with role="option" (under accessibleRole="ListBox") correctly render aria-selected.
• Added Cypress regression test in packages/fiori/cypress/specs/UploadCollection.cy.tsx asserting that UploadCollectionItem retains role="listitem" without rendering aria-selected.
• Aligned assertions in packages/fiori/cypress/specs/UserSettingsDialog.cy.tsx for items with role="listitem".

Fixes: #14235