feat(layout-engine): render table headers, tblLook support#2256

harbournick merged 2 commits intomainsuperdoc-dev/superdoc:mainfrom

nick/sd-2086-header-row-shading-dropped-on-render-when-added-via-api-onsuperdoc-dev/superdoc:nick/sd-2086-header-row-shading-dropped-on-render-when-added-via-api-onCopy head branch name to clipboard