[Core] Deserialization of PyArrow Extension Arrays by registration of deserializers

[pimdh]

Why are these changes needed?

This feature adds the ability to (de)serialize arbitrary PyArrow extension arrays. This is needed to use Ray in code bases that use extension arrays.

The serialization already seemed sufficiently general, but as far as I can tell, the deserialization can not be done in generality. Hence, this setup allows registration of custom deserializers for extension types.

For serialization, the selector has been changed from ExtensionType to BaseExtensionType to accommodate for non-Python ExtensionArrays, like pyarrow.FixedShapeTensorArray.

This is at the moment a proof-of-concept. If you like the idea, I suppose the registration function may need to move to a better place, and docs need adding.

Related issue number

Closes #51959

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