refactor: reduce exported members of docusaurus router

[Josh-Cena]

Breaking changes

If you imported some undocumented member of @docusaurus/router (that's not one of useLocation, useHistory, matchPath, or Redirect), it is no longer be available. You need to import directly from react-router-dom instead.

Motivation

1. This makes further refactors/upgrades less risky
2. We are going to do breaking changes with the React router v6 migration anyways, because the useHistory hook doens't exist: https://reactrouter.com/docs/en/v6/upgrading/v5#use-usenavigate-instead-of-usehistory

Have you read the Contributing Guidelines on pull requests?

Yes

[netlify]

✔️ [V2]

🔨 Explore the source changes: 376675d

🔍 Inspect the deploy log: https://app.netlify.com/sites/docusaurus-2/deploys/6204e65966f9c70008f4e828

😎 Browse the preview: https://deploy-preview-6651--docusaurus-2.netlify.app

[github-actions]

⚡️ Lighthouse report for the changes in this PR:

Category	Score
🟠 Performance	77
🟢 Accessibility	100
🟢 Best practices	100
🟢 SEO	100
🟢 PWA	92

Lighthouse ran on https://deploy-preview-6651--docusaurus-2.netlify.app/

[github-actions]

Size Change: -3.2 kB (0%)

Total Size: 770 kB

Filename	Size	Change
website/build/assets/js/main.********.js	580 kB	-3.2 kB (-1%)

ℹ️ View Unchanged

Filename	Size
website/.docusaurus/globalData.json	47.8 kB
website/build/assets/css/styles.********.css	105 kB
website/build/index.html	36.7 kB

_{compressed-size-action}

[slorber]

don't we want to do routing breaking changes all at once? why do this in 2 steps?

[Josh-Cena]

I don't even have a plan for the RR v6 transition—probably going to be quite a while, considering the difficulty. Also, this breaking change is quite low-impact and migration is quite easy, compared to the useHistory transition that's going to happen afterwards. I'd rather make the migration more progressive.

[slorber]

ok why not, it shouldn't affect much users and there's a good workaround anyway