Add Kosovo flag style for high res flags (bl00mber#404)

Author: rodilo

src/style/common/high-res-flags.less

@@ -127,6 +127,7 @@
  .kg { background-position: -288px -168px; }
  .kh { background-position: -312px -168px; }
  .ki { background-position: -336px -168px; }
+ .xk { background-position: -144px 0px; }
  .km { background-position: -360px -168px; }
  .kn { background-position: -384px -168px; }
  .kp { background-position: -0px -192px; }