[wip] Highlight wp table columns on hover

Bug # 9208 (Task #10561)

Signed-off-by: Alex Coles <alex@alexbcoles.com>
Display column highlight only on header hover

Signed-off-by: Alex Coles <alex@alexbcoles.com>
Merge pull request #1592 from opf/feature/wp-table-column-highlighting

Feature/wp table column highlighting