Alternates media in multiple generated sitemap

[hsoulier]

Goals

1. Be able to add other alternates values other than languages in multiple generated sitemaps.

Non-Goals

No response

Background

For now, when you we want to add a media alternate in sitemap there is a difference between the static sitemap and the dynamic one.

Proposal

Update the function resolveSitemap

...
for (const item of data) {
    content += '<url>\n'
    content += `<loc>${item.url}</loc>\n`

    const languages = item.alternates?.languages
    if (languages && Object.keys(languages).length) {
      // Since sitemap is separated from the page rendering, there's not metadataBase accessible yet.
      // we give the default setting that won't effect the languages resolving.
      for (const language in languages) {
        content += `<xhtml:link rel="alternate" hreflang="${language}" href="${
          languages[language as keyof typeof languages]
        }" />\n`
      }
    }

	const medias = item.alternates?.media
	if (medias && Object.keys(medias).length) {
      for (const media in medias) {
        content += `<xhtml:link rel="alternate" media="${media}" href="${
          medias[media as keyof typeof medias]
        }" />\n`
      }
    }
...