refactor(cell, header): use headerCell.id for aria-describedby

Author: ddaribo

projects/igniteui-angular/src/lib/grids/cell.component.ts

@@ -517,8 +517,7 @@ export class IgxGridCellComponent implements OnInit, OnChanges, OnDestroy, CellT
     /** @hidden @internal */
     @HostBinding('attr.aria-describedby')
     public get ariaDescribeBy() {
-        let describeBy = this.grid.headerGroupsList
-                        .find(hg => hg.column.field === this.column.field)?.headerID || '';
+        let describeBy = this.column.headerCell?.id || '';
         if (this.isInvalid) {
             describeBy += ' ' + this.ariaErrorMessage;
         }

projects/igniteui-angular/src/lib/grids/headers/grid-header.component.ts

@@ -55,6 +55,13 @@ export class IgxGridHeaderComponent implements DoCheck, OnDestroy {
     @ViewChild('sortIconContainer', { read: ElementRef })
     protected sortIconContainer: ElementRef;
 
+    /**
+     * @hidden
+     */
+    @Input()
+    @HostBinding('attr.id')
+    public id: string;
+
     /**
      * Returns the `aria-selected` of the header.
      */