[ADF-4213] drop events for DataTable component (#4589)

* stub for demo shell

* drop events for datatable

* fix docs

* cleanup template

* remove unused attribute

* disable spellcheck for the demo file

lib/core/datatable/components/datatable/datatable.component.ts

@@ -701,4 +701,51 @@ export class DataTableComponent implements AfterContentInit, OnChanges, DoCheck,
         const name = this.getNameColumnValue();
         return name ? row.getValue(name.key) : '';
     }
+
+    onDragOver(event: Event) {
+        event.preventDefault();
+    }
+
+    onHeaderDrop(event: Event, column: DataColumn) {
+        event.preventDefault();
+
+        this.elementRef.nativeElement.dispatchEvent(
+            new CustomEvent('header-drop', {
+                detail: {
+                    target: 'header',
+                    event,
+                    column
+                },
+                bubbles: true
+            })
+        );
+    }
+
+    onCellDrop(event: Event, column: DataColumn, row: DataRow) {
+        event.preventDefault();
+
+        this.elementRef.nativeElement.dispatchEvent(
+            new CustomEvent('cell-drop', {
+                detail: {
+                    target: 'cell',
+                    event,
+                    column,
+                    row
+                },
+                bubbles: true
+            })
+        );
+    }
+
+}
+
+export interface DataTableDropEvent {
+    detail: {
+        target: 'cell' | 'header';
+        event: Event;
+        column: DataColumn;
+        row?: DataRow
+    };
+
+    preventDefault(): void;
 }