Allow column alignment (left/center/right) for table columns

This could be a prop that sets utility class for each table column, something like

```jsx

...

```

Valid values would be `left`, `center`, or `right` - defaulting to `left`.

This could be set for `TableHeader` or `TableCell`.

Start by locating the TableHeader and TableCell component implementations and checking how table utility classes are currently applied. Decide where the alignment prop belongs, support left, center, and right with left as the default, and verify the resulting table-column alignment with the relevant component tests.

Written by the indexing model from the issue text.