refactor(grid-row): add index to grid.page and grid.perPage derivative #5770

- chore(grid/hGrid): update describes

Author: jackofdiamond5

projects/igniteui-angular/src/lib/grids/grid/grid-row-selection.spec.ts

@@ -1875,7 +1875,7 @@ describe('IgxGrid - Row Selection #grid', () => {
         }));
     });
 
-    describe('Custom selectors', () => {
+    describe('Custom row selectors', () => {
         let fix;
         let grid;
 
@@ -1929,7 +1929,7 @@ describe('IgxGrid - Row Selection #grid', () => {
             fix.detectChanges();
 
             const firstRootRow = grid.getRowByIndex(0);
-            expect(firstRootRow.nativeElement.querySelector('.rowNumber').textContent).toEqual('30');
+            expect(firstRootRow.nativeElement.querySelector('.rowNumber').textContent).toEqual('15');
         });
     });
 });

projects/igniteui-angular/src/lib/grids/grid/grid-row.component.html

@@ -11,8 +11,8 @@
          <ng-template *ngTemplateOutlet="
             this.grid.rowSelectorTemplate ? this.grid.rowSelectorTemplate : rowSelectorBaseTemplate;
             context: { $implicit: {
-                            index: (this.grid.groupingExpressions ? this.grid.filteredSortedData.indexOf(this.rowData) : this.index) +
-                             this.grid.page * this.grid.perPage,
+                            index: this.grid.groupingExpressions.length > 0 ? this.grid.filteredSortedData.indexOf(this.rowData) : 
+                                this.index + this.grid.page * this.grid.perPage,
                             rowID: rowID, selected: selected }}">
         </ng-template>
     </div>

projects/igniteui-angular/src/lib/grids/hierarchical-grid/hierarchical-grid.selection.spec.ts

@@ -742,7 +742,7 @@ describe('IgxHierarchicalGrid selection #hGrid', () => {
         });
     });
 
-    describe('Custom selectors', () => {
+    describe('Custom row selectors', () => {
         let hGrid;
         let firstLevelChild;