page-break-before: always and page-break-after: always on a table row are ignored #591

Part of #552 (step 28, values read wrongly).

page-break-before: always and page-break-after: always on a table row are ignored. Only avoid is read on rows.

Measured on gravitypdf at 60b82630, PHP 8.5.4.

CSS Fragmentation applies break-before and break-after to table rows. CSS 2.1 left rows to the user agent.

Cause. Tr::open() stores a row's break only when it is avoid (src/Tag/Tr.php:21-29). It maps page-break-after onto pagebreak-before of the next row. _tableWrite() reads the markers only to keep rows together (src/Mpdf.php:23184-23190).

Fix.

• Store always (and left/right, as always) in the same pagebreak-before list, with after mapped onto the next row as now.
• In _tableWrite(), when a row is marked, break the table before it with the same code an overflowing row uses, so the header and footer rows repeat.
• Ignore a break before the first body row, and inside a nested table, where the outer table decides the breaks. Keep the !ColActive condition the avoid markers have.

#569 reads break-before: page as page-break-before: always, so rows get it once this lands. #576 does the same for page-break-before on the table itself.

Tests. always before and after a row, on a row in thead and in tfoot, on the first and the last row, in a nested table, and with a repeated header. Record which page each cell's text is drawn on.