[Feature]: ArrayShape describer

[yann-eugone]

Description

For the moment, it is the DictionaryDescriber that describes every Symfony\Component\TypeInfo\Type\ArrayShapeType, because it is a subtype of Symfony\Component\TypeInfo\Type\CollectionType.

But a better API description can be generated for this type, because we know the properties from the description.

I suggest to write a dedicated ArrayShapeDescriber.
And update DictionaryDescriber to exlude every ArrayShapeType.

Additional context

I'll be happy to contribute and add this describer myself if you think it's interesting.