chore: add datatype new_list

[fansehep]

Which issue does this PR close?

Closes #4544

Rationale for this change

What changes are included in this PR?

Are there any user-facing changes?

add a simple func to and the default name is "item".

[tustvold]

I think for consistency with Field::new_list we should take the item name as an argument. Thoughts @alamb ?

[alamb]

I personally think we should use the standard / convention "item" always (not take a new parameter) to encourage people to follow the convention. If people want a different name, they can construct the DataType directly.

In terms of consistency with, https://docs.rs/arrow/latest/arrow/datatypes/struct.Field.html#method.new_list I would recommend we remove the name parameter from that method, due to the same rationale above

[tustvold]

recommend we remove the name parameter from that method

It can't be removed, it is part of the field parameter that is passed in, which needs to be kept for nullability, metadata, etc... I just think it will be more confusing for users if some APIs specify "item" and some don't

[alamb]

I just think it will be more confusing for users if some APIs specify "item" and some don't

I don't think it will increase confusion as it is already there: "I am making a list, what name should I use for its child" when the name never is used

To reduce the confusion I think we should reduce the need for specifying that field name ever when making lists

[alamb]

Thank you @fansehep

[alamb]

I think this method will be helpful and make downstream code working with Lists easier to manage. Thank you @fansehep

[alamb]

@tustvold and I had some conversation about this PR that I wanted to add as context

I believe this PR is a step forward because the way DataType::List is represented in arrow-rs forces the user to pick a name for something that is essentially anonymous ("item") is very confusing.

So in my mind, it is a really bad user experience that users have know to cargo cult "item". For example DataFusion copies "item" in several places:

https://github.com/search?q=repo%3Aapache%2Farrow-datafusion%20%5C%22item%5C%22&type=code

I believe that @tustvold is worried that hiding the details of DataType::List construction also hides the construction of the Field (and thus encourages use of the API that might lose field level metadata)

While this is probably fine, it seems a bit incoherent to have some APIs in terms of DataType and some Field.

I plan follow on PRs to:

1. Clarify the documentation that DataType::new_list does not carry forward field metadata
2. Try and add Field::new_list_item or something

[alamb]

Thanks again @fansehep

[alamb]

Follow on: #4627