This normalizes the `asPath` for `getServerSideProps` and `getStaticProps` pages to ensure it matches the value that would show on the client instead of a) the output pathname when revalidating or generating a fallback or b) the `_next/data` URL on client transition. 

Fixes: https://github.com/vercel/next.js/issues/16542

Earlier today #17038 was merged which I opened to fix a problem when using `webpack@5.0.0-beta.30` with Next.js using the new Webpack 5 support. In that PR, the only change was the renaming of a configuration key. I later discovered that the change on the Webpack side was different than I initially thought, and this meant that the fix I submittted to Next.js didn't work.

This PR intends to fix the remaining problems. Webpack 5 now accepts a `environment` key that can be used to configure the target output. Previously, this was known as `ecmaVersion` and accepted a number. Now, `environment` accepts a configuration object with individual options. I've configured this in such a way where it resembles an ES5 environment:
```js
environment: {
   arrowFunction: false,
   bigIntLiteral: false,
   const: false,
   destructuring: false,
   dynamicImport: false,
   forOf: false,
   module: false,
}
```

This uses the "Expand directories" feature introduces in Prettier 2.0 to automatically format all supported file types.

Also, I fixed some badly formatted files.

For some reason babel-plugin-syntax-jsx of babel 6 was used instead of
babel 7 version.

Throughout some of the blog examples word `formatter` is spelled as `formater`, this PR changes all of them to `formatter`

This PR fixes #17035. As described in the issue, there was a breaking change in `webpack@5.0.0-beta.30`: `output.ecmaVersion` was replaced by `output.environment`. This meant Next.js apps using this `webpack` version would break. This PR updates the relevant Webpack config.

I think this will break any apps that are still using `webpack@5.0.0-beta.29`, but I don't know whether that is a problem as this is a beta feature. If it is, I'd love it if someone could let me know how to detect beta versions in the code so I can make it backwards-compatible.

Co-authored-by: NJoe Haddad <joe.haddad@zeit.co>

Since [the current link](https://nextjs.org/docs/api-reference/next.config.js/environment-variables) for the build-time environment variables docs recommends the approach outlined in [this section](https://nextjs.org/docs/basic-features/environment-variables), I think the link should point there instead.

ref https://github.com/GoogleChrome/web-vitals/pull/68

won't fail the new [`no-unload-listeners`](https://github.com/GoogleChrome/lighthouse/pull/11085) Lighthouse audit.

Ref https://github.com/webpack-contrib/terser-webpack-plugin/blob/v4.1.0/package.json#L44

cacache is a dependency of terser-webpack-plugin. The latest version
depends on cacache 15 while next adds cacache 13. This may give
unexpected results. Better keep it in sync with terser plugin.

Babel-preset-env includes includes optional chaining and
nullish-coalescing since [7.8.0](https://github.com/babel/babel/releases/tag/v7.8.0).

In this diff I removed these plugins from next preset to prevent
dependency duplication when their newer versions are out.

The new version replaced big clone-deep package with dependency-free klona
- https://github.com/webpack-contrib/sass-loader/releases/tag/v10.0.0
- https://github.com/webpack-contrib/sass-loader/releases/tag/v9.0.0

Also deduped some related transitives.

There was a security update for node-fetch.

> This is an important security release. It is strongly recommended to update as soon as possible.
https://github.com/node-fetch/node-fetch/blob/master/docs/CHANGELOG.md#v261

Closes: https://github.com/vercel/next.js/issues/14433

Co-authored-by: NJoe Haddad <joe.haddad@zeit.co>

This adds an error when interpolation fails to make sure invalid `href`s aren't accidentally used and an invalid URL is built. 

Closes: https://github.com/vercel/next.js/issues/16944

Fixes #16444

Fixes #10508

Fixes https://github.com/vercel/next.js/issues/16147

This makes sure we properly resolve a rewrite when only the `href` value is used. This was causing a full-reload and was missed in the existing test since we weren't making sure a full navigation didn't occur which has been added in this PR. 

Fixes: https://github.com/vercel/next.js/issues/16974

Fixes #10142
Fixes #11629

## Changelog

- Updated slate.js to version 0.58.4
- Removed unused packages (immutable & slate-plain-serializer)
- Simplified example (we don’t need to demonstrate the multi editor case anymore, since this issue is now handled by slate internally)
- Remove deprecated `KeyUtils`
- Removed deprecated Components

## Related:

- https://github.com/ianstormtaylor/slate/issues/870

As the example is about Yarn workspaces, it should gitignore `.next` recursively.