chore(*): fix lint build errors

Author: igdmdimitrov

projects/igniteui-angular/src/lib/core/styles/components/_index.scss

@@ -25,7 +25,7 @@
 @forward 'grid/pivot-data-selector-theme';
 @forward 'grid-summary/grid-summary-theme';
 @forward 'grid-toolbar/grid-toolbar-theme';
-@forward 'highlight/highlight-theme.scss';
+@forward 'highlight/highlight-theme';
 @forward 'icon/icon-theme';
 @forward 'icon-button/icon-button-theme';
 @forward 'input/input-group-theme';
@@ -50,5 +50,5 @@
 @forward 'time-picker/time-picker-theme';
 @forward 'toast/toast-theme';
 @forward 'tooltip/tooltip-theme';
-@forward 'tree/tree-theme.scss';
+@forward 'tree/tree-theme';
 @forward 'watermark/watermark-theme';