chore(*): Add missing context.

Author: MKirova

projects/igniteui-angular/src/lib/grids/grid-base.directive.ts

@@ -1373,7 +1373,7 @@ export abstract class IgxGridBaseDirective extends DisplayDensityBase implements
      * The custom template, if any, that should be used when rendering a row expand indicator.
      */
     @ContentChild(IgxExcelStyleHeaderIconDirective, { read: TemplateRef })
-    public excelStyleHeaderIconDirectiveTemplate: TemplateRef<any> = null;
+    public excelStyleHeaderIconDirectiveTemplate: TemplateRef<IgxGridHeaderTemplateContext> = null;
 
     /**
      * Gets the excel style header icon.