Top app bar - Update action icons customization

[paulinea]

In the demo app, the user should be able to see the top app bar component with 0, 1, 2 or 3 action icons.

Add a chips customization option in the bottom sheet: "Action count" with values "0", "1", "2", "3".

The last element displayed in the top app bar must be an avatar

When no action avatar is displayed, "Action avatar" option is disabled.
When no action icon is displayed, "Action icon badge" option is disabled.

[B3nz01d]

Finished during Sprint # 26