For buttons representing node inputs (e.g. in the material properties)
rather than drawing some generic socket icon, the actual sockets are
drawn now. That includes color, shape and the selection outline.
This should make it easier to understand what these buttons relate to.
Screenshots: {F8469252}, {F8469248} (The left alignment will be done in
a follow-up commit.)
Differential Revision: https://developer.blender.org/D7409
Reviewed by: Brecht Van Lommel, Clément Foucault, William Reynish
675d42dfc3