refactor(theme-classic): split sidebar into smaller parts

[slorber]

Motivation

This should help to customize the sidebar with swizzling.

For example to add sticky sidebar ads as requested here: #5468 (comment)

Also reduce content to eject for some other customizations such as https://docs.dyte.io/

Have you read the Contributing Guidelines on pull requests?

yes

Test Plan

preview

dogfood sidebar content wrapping on test instance

https://deploy-preview-6844--docusaurus-2.netlify.app/tests/docs

---

Notes:

• I only refactored/split, no behavior change expected
• just removed some classes that looked unused
• I'm not 100% sure yet components have the best naming, nested structure and split
• Not marking those components as swizzle safe yet, but still useful for users even if it stays unsafe

@Josh-Cena any opinion?

[netlify]

✔️ [V2]

🔨 Explore the source changes: 34722fd

🔍 Inspect the deploy log: https://app.netlify.com/sites/docusaurus-2/deploys/622a0f26079ab300094ac0b6

😎 Browse the preview: https://deploy-preview-6844--docusaurus-2.netlify.app

[github-actions]

⚡️ Lighthouse report for the changes in this PR:

Category	Score
🟠 Performance	60
🟢 Accessibility	100
🟢 Best practices	92
🟢 SEO	100
🟢 PWA	90

Lighthouse ran on https://deploy-preview-6844--docusaurus-2.netlify.app/

[github-actions]

Size Change: -228 B (0%)

Total Size: 792 kB

Filename	Size	Change
website/build/assets/css/styles.********.css	105 kB	-228 B (0%)

ℹ️ View Unchanged

Filename	Size
website/.docusaurus/globalData.json	49.9 kB
website/build/assets/js/main.********.js	598 kB
website/build/index.html	38.7 kB

_{compressed-size-action}

[Josh-Cena]

This makes sense! Will we port the same structure to Navbar and Footer?

[slorber]

This makes sense! Will we port the same structure to Navbar and Footer?

Yes that's the goal, going to open other similar PRs to other parts of the theme.

Is this PR good enough to merge for you?

[Josh-Cena]

Is this PR good enough to merge for you?

Yes 👍 You can merge this if you are ready

[slorber]

ok the CI is failing due to Node 17.7: nodejs/node#42279

Will fix to use 17.6 temporarily

[slorber]

hmm looks useless to care about it, the fix is released very soon: nodejs/node#42285