Move border painting functions from RenderBoxModelObject there.
<rdar://problem/99594391>
Created attachment 462162 [details] Patch
Created attachment 462175 [details] Patch for landing
Committed 254214@main (66ab9a4c5a45): <https://commits.webkit.org/254214@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 462175 [details].