fix(grid): Keep RTL in mind

Signed-off-by: MPopov <[email protected]>

Author: MPopov

projects/igniteui-angular/src/lib/core/styles/components/grid/_grid-theme.scss

@@ -1340,7 +1340,7 @@
         display: flex;
         align-items: center;
         justify-content: center;
-        margin-right: rem(8px);
+        margin-#{$right}: rem(8px);
         cursor: pointer;
 
         igx-icon {