Slightly enlarge Snak type (custom/unknown/no value) icons

All this really does is making the icons visually larger. The
16x16 pixel canvas stays the same. Reasons for this change are:
* Make the icon easier to hit with the mouse (even if this patch
  does not change the hit box, it feels like it's easier to hit).
* Make the icon size closer to the rank icon next to it. Currently
  they are so different, they feel kind of misplaced.

Bug: 57663
Change-Id: Ie3fa879b09b5edcaeecba4085e0687da382e6d78
Merge "Slightly enlarge Snak type (custom/unknown/no value) icons"