PaginatedDataTable2State.dispose() needs to detach from its PaginatorController.

[devrelm]

PaginatedDataTable2State.dispose() does not call controller.detach() in its dispose() method:

https://github.com/maxim-saplin/data_table_2/blob/879f9baa25751dd928d2cc8511d95d519cd551bb/lib/src/paginated_data_table_2.dart#L580-L583

Right now, a consumer that passes a PaginatedController into a PaginatedDataTable2 is unable to use PaginatorController.isAttached to tell whether they can safely call any of the methods on the controller.