feat(content-blog): include front matter in loaded content metadata

[Josh-Cena]

Motivation

In the spirit of plugin enhancement (#4492) we should allow users to declare additional server-side metadata through front matter. #4495 added the front matter to doc metadata; we should do the same for blog posts as well.

This has been requested on Discord.

Have you read the Contributing Guidelines on pull requests?

Yes

[netlify]

✔️ [V2]

🔨 Explore the source changes: 0290777

🔍 Inspect the deploy log: https://app.netlify.com/sites/docusaurus-2/deploys/61c6a700e6cf7600078ea2f6

😎 Browse the preview: https://deploy-preview-6189--docusaurus-2.netlify.app

[github-actions]

⚡️ Lighthouse report for the changes in this PR:

Category	Score
🟠 Performance	68
🟢 Accessibility	98
🟢 Best practices	100
🟢 SEO	100
🟢 PWA	95

Lighthouse ran on https://deploy-preview-6189--docusaurus-2.netlify.app/

[github-actions]

Size Change: 0 B

Total Size: 662 kB

ℹ️ View Unchanged

Filename	Size
website/.docusaurus/globalData.json	40.1 kB
website/build/assets/css/styles.********.css	102 kB
website/build/assets/js/main.********.js	490 kB
website/build/index.html	29.6 kB

_{compressed-size-action}

[KELEN]

nice, i also need it. please mr

[Josh-Cena]

@KELEN Merged. Please test with canary release

[KELEN]

@Josh-Cena canary version has error Can't find docs preferred context, maybe you forgot to use the "DocsPreferredVersionContextProvider"?

[Josh-Cena]

Seems like a distinct issue. This PR doesn't even change docs-related code. Could you send another issue with your code sample / a minimal repro?

[honlyHuang]

@Josh-Cena canary version has error Can't find docs preferred context, maybe you forgot to use the "DocsPreferredVersionContextProvider"?

I also encountered this problem. How did you solve it in the end？

[slorber]

@honlyHuang please try to run the docusaurus clear command, and remove/update your swizzled components too

This is likely an issue with your site, unless you are able to provide a small repro

[honlyHuang]

@slorber Thx! I solved it. The reason is that I upgraded from beta.8 to beta.15, and the plugin configuration has not been updated.