Extended Border support in Aurorae

Aurorae Themes can make use of the extended borders feature to allow
resizing outside the window decoration area. So far only Plastik makes
use of it in the Tiny border case.

This should be extended in future by adding generic NoSideBorders and
NoBorders sizes as used by Oxygen.

FEATURE: 308992
FIXED-IN: 4.11
REVIEW: 107936