What is this feature?

This has moved over from #108074, but without the wrapText enablement for DataLinks, and thus without the changes necessary to row height stuff, freeing up the change to be less risky overall.

A number of style cleanups for TableNG, primarily centering around text overflow and presentation of some text-driven cell types.

• Updates JSONCell, AutoCell, and DataLinksCell to ensure the inner contents are display: inline, and updates the cell class to explicitly use text-overflow: ellipsis, to ensure that overflowing text from these cell types has ellipses.
• DataLinksCell now have a border between each link.
• DataLinksCell now has a textWrap option like other text-based cells, and the calculation for its contents correctly derives its height from the concatenated content of the datalinks titles.
• utilities which sniff the type of the field were updated to treat DataLinkCell as a special case for text alignment and text overflow, since the field type of a DataLinkField isn't relevant to what is actually rendered.
• decoupled text alignment and content justification utils, since we the text-based cell types are all display: inline now and using text-align is a more appropriate way to style that content.
• updated the hover overflow class to also include [data-selected=true], which is a data attribute managed by react-data-grid on keyboard navigation.
  • added a box shadow to the selected or hovered cell to make it more legible compared with the inactive cells "below" it.
  • updated DataLinkCell to make hover overflow work as expected.

Special notes for your reviewer:

Please check that:

• It works as expected from a user's perspective.
• If this is a pre-GA feature, it is behind a feature toggle.
• The docs are updated, and if this is a notable improvement, it's added to our What's New doc.