This PR was squashed before being merged into the 5.3-dev branch.

Discussion
----------

[Config] Use plural name on array values

| Q             | A
| ------------- | ---
| Branch?       | 5.x
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Tickets       |
| License       | MIT
| Doc PR        | Related: symfony/symfony-docs#15264

If we have a PrototypedArrayNode and the prototype is does not have a key (`->useAttributeAsKey('name')`). Then we know for sure that the value should be an array.

See this example from `$framework->assets()`

```diff
    /**
+    * @param list<mixed>
     * @return $this
     */
-   public function baseUrl($value): self
+   public function baseUrls(array $value): self
    {
        $this->baseUrls = $value;

        return $this;
    }
```

Commits
-------

f564a7a [Config] Use plural name on array values