This changeset modifies the Site Health panel for HTTPS to provide more accurate recommendations based on whether the environment is already set up for HTTPS.
* Introduces `wp_is_using_https()` to check whether the site is configured to use HTTPS (via its Site Address and WordPress Address).
* Introduces `wp_is_https_supported()` to check whether the environment supports HTTPS. This relies on a cron job which periodically checks support using a loopback request.
Props Clorith, flixos90, miinasikk, westonruter.
Fixes#47577.
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