Add short_item_threshold config option

[123vivekr]

Allow custom short item threshold values via config

Closes #5225

[calebcartwright]

Awesome thank you! I forgot to include one very important step, my apologies. We should also include some test cases with the snippets provided in #5225 to show the new config option in use.

I think it should suffice to add two input files (one with the default value for the new opt, and one with an overridden value) under tests/source/configs and then their corresponding resultant files under tests/target/configs

[123vivekr]

It is done. Thanks a lot for your help @calebcartwright

[calebcartwright]

Changes look good, thank you! Couple minor items left inline for you

[calebcartwright]

I almost feel like I need to apologize for this question, but after reflecting a bit more I'm not sure short_item is really the best moniker. I say that both because "item" is a very overloaded term in general but has specific meanings in Rust in particular including in other configuration options, and also because the option name doesn't really convey what it does in and of itself.

Curious what you, and anyone else, think @123vivekr? Would something like... short_array_element_threshold be less ambiguous?

[ytmimi]

Would something like... short_array_element_threshold be less ambiguous?

I think the name is less ambiguous, but I wonder if it fully conveys its purpose. A long one, but what about simple_array_element_width_threshold. I also wonder if we should add more to the description in Configurations.md. Maybe its worth defining what a "simple" array element is and explain that this value controls Mixed array element formatting.

[calebcartwright]

I also wonder if we should add more to the description in Configurations.md.

Agreed, I was saying the same in #5228 (comment) though it may not have been clear I was asking for both description updates and examples.

How about something along the lines of this (please feel free to wordsmith):

The length limit of an array element in order for the element to be considered "short".

The layout of an array's elements is dependent on the length of each of those elements. If the length of every element in an array is below this threshold (all elements are "short") then the array can be formatted in the mixed/compressed style, but if any one element has a length that exceeds this threshold then the array elements will have to be formatted vertically

[123vivekr]

@calebcartwright @ytmimi I went with short_array_element_width_threshold which sounded more accurate.

@calebcartwright I have also added your description to the Configurations.md, with a few changes to simplify it.

Do let me know if there is anything I could help with. :)

[calebcartwright]

Excellent, thanks so much!