Added new vector graphics for tray window header icons

Signed-off-by: Dominique Fuchs <32204802+DominiqueFuchs@users.noreply.github.com>

theme/white/caret-white.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" height="16" width="16" version="1.1" viewbox="0 0 16 16"><path d="M4 6l4 4 4-3.994z" fill="#fff"/></svg>

theme/white/folder.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 16 16" width="16" version="1.1" height="16"><path fill="#fff" d="m1.5 2c-0.25 0-0.5 0.25-0.5 0.5v11c0 0.26 0.24 0.5 0.5 0.5h13c0.26 0 0.5-0.241 0.5-0.5v-9c0-0.25-0.25-0.5-0.5-0.5h-6.5l-2-2z"/></svg>