DataTable component does not implement proper keyboard navigation for grid pattern

The `DataTable` component uses the `grid` ARIA role, but doesn't implement the keyboard navigation and focus patterns described at https://www.w3.org/WAI/ARIA/apg/patterns/grid/. In particular:

1. It uses the same "1D" navigation as other list-like components such as menus or selects, instead of 2D navigation where left/right moves between cells and up/down moves between rows.
2. It sets focus only on the rows, not individual cells
3. When pressing up on the first row or down on the last row, navigation wraps, whereas it shouldn't.