Permalinks: Follow rewrite rules for trailing slashes in `paginate_links()`.

Modifies the default settings of `paginate_links()` to only include trailing slashes, eg `example.org/page/2/`, when the permalink settings include a trailing slash. When the permalink settings do not include a slash, neither do the generated links, eg `example.org/page/2`.

This prevents the generated links from hitting a URL that subsequently redirects when the permalink structure does not include a trailing slash.

Props adamsilverstein, ankitkumarshah, audrasjb, hmbashar, huzaifaalmesbah, joedolson, juanmaguitar, krupajnanda, mai21, ozgursar, peterwilsoncc, rahulsprajapati, sirlouen, welcher, westonruter.
Fixes #61393.


git-svn-id: https://develop.svn.wordpress.org/trunk@62036 602fd350-edb4-49c9-b593-d223f7449a82