The tabular review request field component gave every header cell a

pointer cursor, while the hover underline that goes with sorting was

correctly limited to headers with the -is-sortable class. Tables

that can't be sorted, such as the commit list, invited a click that

does nothing.
The cursor now follows the same modifier as the underline.

Created a WIP review request field that uses the tabular styles but

does not allow sorting. Saw that the cursor no longer indicated

clickability.