fix(grid): Export range selection interface

Closes #6274

Author: rkaraivanov

projects/igniteui-angular/src/lib/grids/common/events.ts

@@ -7,7 +7,7 @@ import { IgxGridCellComponent } from '../cell.component';
 import { IgxColumnComponent } from '../columns/column.component';
 import { IgxGridBaseDirective } from '../grid-base.directive';
 import { IgxRowDirective } from '../row.directive';
-
+export { GridSelectionRange } from '../selection/selection.service';
 
 export interface IGridClipboardEvent {
     data: any[];