Sync Table with UXPin

[scurker]

Changes:

• Thicker border between TableHeader / TableBody (vertical and horizontal) for bordered variant
• Fix the sizing of the sort iconography (when sorted, the icon is slightly displaced)
• For sortable table headers, change the icon from space-between to flex-start
• Update sort up / down icon so it's not as large and matches UXPin
• Add a note to documentation to recommend that authors indicate the current sorted column by default:

  • As a best practice, when a table has sorted columns an author should indicate which column is currently sorted by setting the sort direction for the active sorted column.

UXPin Design System: https://app.uxpin.com/design-system/c933c74928e2195cc540/ui-patterns/213536

[bobbyomari]

This has been completed and is part of #1154