Replacing global themed sass-vars to css-vars (#4322)

* generating css-vars
* convert all global / theme sass vars to css vars with available default theme colors
* added missing colors to dark lens theme

src/renderer/components/spinner/spinner.scss

@@ -43,7 +43,7 @@
   }
 
   &.singleColor {
-    @include spinner-color($textColorPrimary);
+    @include spinner-color(var(--textColorPrimary));
     animation: $rotateAnimation;
   }