Create a new visual design for action buttons

- Create a new style for two action buttons.
- Change the layout of two_action_buttons.
  Since we use same style for positive/nagative
  buttons now, we only remain button1/button2 for
  this layout.
- Create a setButtonIcon interface in ActionButtonPreference.
  So, user can set icon for each button in this preferece.

Test: visual, robotest
Bug: 116346008
Change-Id: I511272cba5fd961349b85cae6d30004ddabe2c8e