fix(MultiSelect): #8102 - keyboard navigation and scrolling from wrapper

[Luko248]

Description

Fixes #8102

This PR improves keyboard navigation and scrolling behavior in MultiSelect component:

• Prevent page scroll on Space when wrapper has focus
• ArrowUp/Down enter and move options from wrapper
• Auto-scroll wrapper to keep focused option visible (both directions)
• Escape closes and returns focus to trigger
• Add onKeyDown+tabIndex to wrapper/virtual list; data-p-index on items

Changes

• Enhanced keyboard navigation from wrapper element
• Improved auto-scrolling to keep focused options visible
• Better focus management when closing with Escape key
• Added necessary attributes for accessibility (tabIndex, data-p-index)

Type of change

• [x] Bug fix (non-breaking change which fixes an issue)

Testing

Please test keyboard navigation in MultiSelect component:

1. Open MultiSelect panel
2. Use Arrow keys to navigate through options
3. Press Space to select/deselect
4. Verify auto-scrolling works correctly
5. Press Escape to close and verify focus returns to trigger

[melloware]

set to PrimeTek to review.