Configuration for trailing commas does not affect macros defined with lists

Formatting for vec! macros will always follow a trailing_comma = "Vertical" style. Lists small enough to fit into one line will ignore a setting of "Always", while lists large enough to be displayed vertically will ignore "Never".

With no other configuration changes this code block will always be formatted to the following regardless of the setting for trailing commas:

    let short = vec![1.0, 2.0, 3.0];
    let long = vec![
        1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, 15.0, 16.0,
        17.0, 18.0, 19.0, 20.0,
    ];

This likely applies to any other macro defined by a list as well, but vec! was what I found the issue with and I'm not sure off the top of my head if there are other macros defined by rust that engage with lists in this way.

Start by reproducing the reported vec! formatting with trailing_comma set to "Always", "Never", and "Vertical" in rustfmt. Check whether other list-like macros show the same behavior, and consider the issue done when short and vertically formatted lists consistently follow each setting.