Add focus ring for focusable elements for better accessibility and consistancy

[vollowx]

Refs:

• Material Web (Source)
• Mixed Components (demo no longer available) (Source)

[zdhxiong]

Currently, we support styling elements with focus states when navigating using tab and arrow keys. However, the Material Design 3 guidelines do not currently define a focus ring. If such a definition is provided in future guidelines, we will align accordingly.