feat(theme-common): stable classname for code blocks

[Josh-Cena]

Motivation

Requested here: typescript-eslint/typescript-eslint#4324 (comment)

Have you read the Contributing Guidelines on pull requests?

Yes

[netlify]

✔️ [V2]

🔨 Explore the source changes: d2aea02

🔍 Inspect the deploy log: https://app.netlify.com/sites/docusaurus-2/deploys/61bd6a4459e210000899ca01

😎 Browse the preview: https://deploy-preview-6125--docusaurus-2.netlify.app

[github-actions]

⚡️ Lighthouse report for the changes in this PR:

Category	Score
🟢 Performance	92
🟢 Accessibility	98
🟢 Best practices	100
🟢 SEO	100
🟢 PWA	95

Lighthouse ran on https://deploy-preview-6125--docusaurus-2.netlify.app/

[Josh-Cena]

@armano2 I hope that's what you had in mind? Also, about typescript-eslint/typescript-eslint#4284 (comment), after some inspection I believe you could use .theme-doc-sidebar-item-category-level-1 > div > a. I'd admit it's still not elegant, but less error-prone than using Infima class names. It's still up to you, and as long as it works, it's fine

[github-actions]

Size Change: +235 B (0%)

Total Size: 652 kB

Filename	Size	Change
website/build/assets/css/styles.********.css	101 kB	+206 B (0%)

ℹ️ View Unchanged

Filename	Size	Change
website/.docusaurus/globalData.json	37.8 kB	0 B
website/build/assets/js/main.********.js	484 kB	+29 B (0%)
website/build/index.html	29.3 kB	0 B

_{compressed-size-action}