fix(IgxGrid): copied data should be correct when there is paging enabled #7801

Author: ddincheva

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

@@ -5480,6 +5480,7 @@ export class IgxGridBaseDirective extends DisplayDensityBase implements
         }
 
         for (let [row, set] of selectionMap) {
+            row = this.paging ? row + (this.perPage * this.page) : row;
             row = isRemote ? row - this.virtualizationState.startIndex : row;
             if (!source[row] || source[row].detailsData !== undefined) {
                 continue;