… list alternative types that should be accepted and wrapped in an array (nicolas-grekas)

This PR was merged into the 7.4 branch.

Discussion
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[Config] Add `ArrayNodeDefinition::acceptAndWrap()` to list alternative types that should be accepted and wrapped in an array

| Q             | A
| ------------- | ---
| Branch?       | 6.4
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Tickets       | -
| License       | MIT
| Doc PR        | -

With #58450, we lost some type info when generating config builders, by preventing #44166 to work correctly.

This PR improves the description of config trees by adding an `ArrayNodeDefinition::acceptAndWrap()` method that allows one to declare which alternative types should be accepted at array-node levels. This declaration then triggers the wrapping of such cases into arrays, and also hints the config builder generator so that it can generate more accurate types for configurator methods.

Commits
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a0d0f95 [Config] Add `ArrayNodeDefinition::acceptAndWrap()` to list alternative types that should be accepted and wrapped in an array