Selection in grid context (#2527)

* update action context on selection change

* correctly add ranges rather than a new range for every row

* add required functions to typings

src/sql/base/browser/ui/table/table.ts

@@ -166,6 +166,10 @@ export class Table<T extends Slick.SlickData> extends Widget implements IThemabl
 		this._grid.setData(this._data, true);
 	}
 
+	getData(): Slick.DataProvider<T> {
+		return this._data;
+	}
+
 	get columns(): Slick.Column<T>[] {
 		return this._grid.getColumns();
 	}