Replaces #46581 , submitted to 6.2 instead. This matches with the changes proposed in #47016 and the config builder contained quite a big refactor for comments in 6.x so this avoids nasty conflicts.

Original description:

One of the main benefits of using the new PHP config builders in application code is the ability to use PHP community tooling to autocomplete and validate the configuration. In this light, I think it makes sense to add the correct PHPdocs to make Psalm and PHPstan understand the config builders.

On top of that, as these config classes are live generated, this is not something that can be easily stubbed in the special PHPstan and Psalm Symfony plugins.