Replacing confusing legacy code with core recommended method

[tloureiro]

General template weekly archive link URL constructor was using a confusing method to generate query string:

<?php
sprintf( '%1$s/%2$s%3$sm%4$s%5$s%6$sw%7$s%8$d', home_url(), '', '?', '=', $arc_year, '&amp;', '=', $result->week );

Replaced with add_query_arg function call

[tloureiro]

general-template.php patch

[ocean90]

In 37530:

Template: In wp_get_archives() use add_query_arg() instead of sprintf() to build the archive URL.

Props tloureiro.
Fixes #36414.