Add more actions to cell (#3217)

* Added toggle more actions to cell

* Resolve PR comments
-- Added INotificationService for notification msg

* Reduced ToggleMoreAction to smaller size. So the dropdown could be displayed closer to it instead of at the buttom of the cell.

src/sql/parts/notebook/models/modelInterfaces.ts

@@ -304,9 +304,9 @@ export interface INotebookModel {
 	changeContext(host: string): void;
 
 	/**
-	 * Adds a cell to the end of the model
+	 * Adds a cell to the index of the model
 	 */
-	addCell(cellType: CellType): void;
+	addCell(cellType: CellType, index?: number): void;
 
 	/**
 	 * Deletes a cell