feat(blog): allow processing blog posts through a processBlogPosts function

[OzakIOne]

Motivation

This new option processBlogPost allow the user to modify BlogPost array used in archive page and blog page.

For example the user can filter to only list blogs that were created after year 2020 or sort BlogPost by alphabetical order.

#9840 (review)

blog: {
  path: 'blog',
  processBlogPosts: async ({blogPosts}) =>
      blogPosts.filter(
        (blog) => blog.metadata.date.getFullYear() > 2020,
      ),
}

blog: {
  path: 'blog',
  processBlogPosts: async ({blogPosts}) =>
      blogPosts.sort((a, b) =>
        a.metadata.title.localeCompare(b.metadata.title),
      ),
}

Test Plan

yarn jest docusaurus-plugin-content-blog --watch

Test links

Blog page

Archive page

processBlogPosts documentation

Related issues/PRs

Supersed #9840

Fix #9831

Fix #9827

[netlify]

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[github-actions]

⚡️ Lighthouse report for the deploy preview of this PR

URL	Performance	Accessibility	Best Practices	SEO	PWA	Report
/	🟠 62	🟢 98	🟢 96	🟢 100	🟠 88	Report
/docs/installation	🟠 66	🟢 96	🟢 100	🟢 100	🟠 88	Report
/docs/category/getting-started	🟠 75	🟢 100	🟢 100	🟢 90	🟠 88	Report
/blog	🟠 69	🟢 100	🟢 100	🟢 90	🟠 88	Report
/blog/preparing-your-site-for-docusaurus-v3	🟠 62	🟢 96	🟢 100	🟢 100	🟠 88	Report
/blog/tags/release	🟠 69	🟢 100	🟢 100	🟠 80	🟠 88	Report
/blog/tags	🟠 75	🟢 100	🟢 100	🟢 90	🟠 88	Report

[github-actions]

Size Change: 0 B

Total Size: 992 kB

ℹ️ View Unchanged

Filename	Size
website/.docusaurus/globalData.json	75.4 kB
website/build/assets/css/styles.********.css	114 kB
website/build/assets/js/main.********.js	765 kB
website/build/index.html	37.9 kB

_{compressed-size-action}

[slorber]

Almost looks good

That would also be nice to have an extra test in index.test.ts to cover the fact that the processBlogPost option has an impact on the plugin loadContent result.

For example, take a simple site with 10 blog posts, page size = 3, and provide a processBlogPosts that only take the 4 first blog posts in the list: the resulting number of pages should be 2 instead of 4.

This kind of test ensures the plugin works overall, and covers the fact that applyProcessBlogPosts is called before blogPosts.filter(shouldBeListed), which is important otherwise we would have a bug.

[slorber]

Almost good 👍