[Feature] Improvement required for generating sitemap

[sarpere]

Goals

1. The base function should be optimised to fit all type of content requirements to steadily increase seo scores
2. Video and image tags should be supported by adding into the sitemap interfaces or give ability users to add custom nested url tags

Her are some examples
Video example

<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
    xmlns:video="http://www.google.com/schemas/sitemap-video/1.1">
  <url>
    <loc>https://www.example.com/videos/some_video_landing_page.html</loc>
    <video:video>
      <video:thumbnail_loc>https://www.example.com/thumbs/123.jpg</video:thumbnail_loc>
      <video:title>Grilling steaks for summer</video:title>
      <video:description>
        Alkis shows you how to get perfectly done steaks every time
      </video:description>
      <video:content_loc>
        http://streamserver.example.com/video123.mp4
      </video:content_loc>
      <video:player_loc>
        https://www.example.com/videoplayer.php?video=123
      </video:player_loc>
      <video:duration>600</video:duration>
      <video:expiration_date>2021-11-05T19:20:30+08:00</video:expiration_date>
      <video:rating>4.2</video:rating>
      <video:view_count>12345</video:view_count>
      <video:publication_date>2007-11-05T19:20:30+08:00</video:publication_date>
      <video:family_friendly>yes</video:family_friendly>
      <video:restriction relationship="allow">IE GB US CA</video:restriction>
      <video:price currency="EUR">1.99</video:price>
      <video:requires_subscription>yes</video:requires_subscription>
      <video:uploader
        info="https://www.example.com/users/grillymcgrillerson">GrillyMcGrillerson
      </video:uploader>
      <video:live>no</video:live>
    </video:video>
   .
   .
   .
  </url>
</urlset>

Image Example

<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
    xmlns:image="http://www.google.com/schemas/sitemap-image/1.1">
  <url>
    <loc>https://example.com/sample1.html</loc>
    <image:image>
      <image:loc>https://example.com/image.jpg</image:loc>
    </image:image>
    <image:image>
      <image:loc>https://example.com/photo.jpg</image:loc>
    </image:image>
  </url>
</urlset>

Non-Goals

No response

Background

Current generic sitemap has many restrictions and doesn't allow developers to generate custom sitemaps using generate function. Developers should be free to add any tags to sitemaps. Otherwise, developers will require to implement custom code to generate the sitemap in advence before they publish the website.

Here is the old structure for adding generic sitemap.

/**
 * Update this with the domain of your site
 */
const Config = {
  domain: 'https://www.test.com'
}

export interface Page {
  slug: string,
}

export const createSitemapUrlSet = (pages: Page[]): string => {
  const urlSet = pages.map((page) => (
    `<url>
        <loc>${Config.domain}${page.slug}</loc>
      </url>`
  )).join('');

  return (
    `<urlset 
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xmlns:image="http://www.google.com/schemas/sitemap-image/1.1" 
      xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
      xsi:schemaLocation="http://www.sitemaps.org/schemas/sitemap/0.9 http://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd">
        ${urlSet}
      </urlset>`
  );
};

the code above is an example how to generate the generic sitemap but it's not consistent at all when it comes to compare with the recent development structure.

Proposal

The resolver function for sitemap (resolveSitemap in packages/next/src/build/webpack/loaders/metadata/resolve-route-data.ts) should extended according to desired tags or the function should be more generic to use for adding custom tags.

I would like to investigate to this part if no one doesn't have availability.

Related Tickets: #63411, #61971, #61555