refactor(ui5-shellbar): responsive Improvements

[dobrinyonkov]

Refactor: Responsive Improvements for ui5-shellbar

Summary

This PR enhances the responsive behavior of the ShellBar, ensuring a better user experience across different screen sizes.

Changes

• Introduces a itemsToHide priority based getter which drives the overflow logic
• Introduces a dedicated container for dynamically displayed items and an inner container for overflowed items.
• Detects overlap via container width differences and dynamically hides items to resolve it.
• Optimizes item hiding behavior based on search visibility:
  • When search is hidden → Overflow items disappear first.
  • When search is visible → Content hides first to keep search accessible.
  • When only one content item is left -> Prioritize its visivility by hiding the search button.
• Dynamically adjusts separators to prevent infinite loops in visibility recalculations. They are "packed" with the last items in the left and right in order to disappear together and not cause another relayouting.
• Enchances the auto-expand/collapse for the search field, based on:
  • Available space - the search is auto collapsed if there is not enought space and items start to disappear, until auto opened again when space is available
  • Focused or dirty state - If currently on focus or it has a value the auto mechanism is stopped.
• Related tests are migrated to Cypress

[PetyaMarkovaBogdanova]

can we add this rule to the static state of the elements

[PetyaMarkovaBogdanova]

Deliveries