… `clone` (#6983)

## What's the problem this PR addresses?

This PR fixes a bug when calling `git clone` with Git 2.52.0; currently,
Yarn is executing `git clone "-c core.autocrlf=false" ...`, instead of
the intended `git clone -c core.autocrlf=false ...`, and Git 2.52.0 does
not like the quoted version.

Resolves #6982.

## How did you fix it?

This splits `-c core.autocrlf=false` into separate arguments.

## Checklist

- [x] I have read the [Contributing
Guide](https://yarnpkg.com/advanced/contributing).
- [x] I have set the packages that need to be released for my changes to
be effective.
- [x] I will check that all automated PR checks pass before the PR gets
reviewed.

## What's the problem this PR addresses?

Npm plans to fully remove the `/-/user/org.couchdb.user:<name>`
endpoint. Since we use this endpoint to login, we need to implement
support for the newer `/-/v1/login` endpoint.

## How did you fix it?

A new option, `--web-login`, enables the web login flow (and fallbacks
to the password flow if the web flow isn't supported). This flag is
automatically enabled for the npm registry. This is technically a
breaking change, but since it's the registry that plans to make that
change I think it's ok.

## Checklist

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## What's the problem this PR addresses?

`"type": "mixed"` is not valid JSON Schema. This results in errors in
features such as VS Code's automatic validation:

```
Schema 'Yarn Config (.yarnrc.yml) - Yarnrc configuration files (yarnrc.json)' is not valid:
/properties/httpTimeout/type : must be equal to one of the allowed values
/properties/httpTimeout/type : must be array
/properties/httpTimeout/type : must match a schema in anyOfYAML(768)
```

Resolves #6972

## How did you fix it?

`type` could be omitted completely (it's redundant with `oneOf`) but is
required by the Docusaurus configuration (via
https://github.com/arcanis/react-json-doc?), so I added it as an array.

To prevent further regressions, I added validation of the JSON Schemas
using [AJV](https://ajv.js.org/). If there's a better place for this
test to reside, please let me know.

## Checklist

<!--- Don't worry if you miss something, chores are automatically
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you submit a PR. -->
<!--- Put an `x` in all the boxes that apply. -->
- [x] I have read the [Contributing
Guide](https://yarnpkg.com/advanced/contributing).

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<!-- Check with `yarn version check` and fix with `yarn version check
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| Package name | Version |
| --- | --- |
| `@yarnpkg/cli` | `4.12.0` |
| `@yarnpkg/plugin-git` | `3.1.4` |
| `@yarnpkg/plugin-npm-cli` | `4.4.0` |