[List] Forms mode navigation enablement

The ui5-list component needs a forms mode that allows users to tab through all active elements within the list. Additionally, forms mode should support F6 group skipping to facilitate faster navigation through complex lists with multiple nested UI elements.

Requirements:

• Introduce a forms mode for the ui5-list component.
• In forms mode, users should be able to tab through all active elements within the list.
• Implement F6 group skipping to allow users to quickly navigate between groups of elements in forms mode.
• Ensure that non-forms mode behavior remains unchanged as designed by Fiori, preventing excessive tabbing in complex list structures.