Docs updates for v5 release

[markerikson]

This PR updates the docs with a ton of changes:

• Linked the "Error Messages" page in the sidebar
  • Removed the url-params-polyfill from that page
• Updated React docs links to point to react.dev
• Pasted in the RTK 2.0 migration guide
• Pasted in the Next.js setup guide
• README updates
  • Moved a ton of content from the README into the "Prior Art" page for lack of anywhere better to put it for now
  • Removed the legacy syntax example from the README
  • Updated the install instructions
  • Linked to the RTK docs
  • Emphasized RTK a bunch more
• Updated the API docs
  • Added "createStore is deprecated" sections to createStore and "API Reference"
  • Added similar cautionary notes to the other API ref pages
  • Nuked a bunch of very obsolete info
• Replaced "ES6" mentions with "ES2015" (but will come back and nuke those too shortly) nuked!
• Added API docs for the new utils
• Nuked an ancient dead "Object Spread" page

[codesandbox-ci]

This pull request is automatically built and testable in CodeSandbox.

To see build info of the built libraries, click here or the icon next to each commit SHA.

Latest deployment of this branch, based on commit 173ff78:

Sandbox	Source
JavaScript	Configuration
Vanilla Typescript	Configuration

[netlify]

✅ Deploy Preview for redux-docs ready!

Name	Link
🔨 Latest commit	173ff78
🔍 Latest deploy log	https://app.netlify.com/sites/redux-docs/deploys/656146e76b0bc9000890d802
😎 Deploy Preview	https://deploy-preview-4625--redux-docs.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.