Exporting reports to excel

Exporting to excel the report "requirement test coverage"  is valuable but not available yet. Here is a proposal to cover this point. It should be extended to other table reports easily.
1) the used PhpExcel library is retired since 2015 and is not compatible with php 8. The PhpSpreadSheet library should be used in place of PhpExcel. Install it with Composer in the external folder. A /vendor folder (attached) is created under /external.
2) modify the requirementTest.php as attached.An hyperlink is inserted after the report table to download the excel file.That's it. Hope it helps!