Allow the user to customise the columns displayed in `py list`

Is your feature request related to a problem? Please describe.
I don't find the default display of py list particularly useful. The aliases take up a lot of space and aren't very helpful (they are easily deducible from the rest of the data). Ideally, I'd like to be able to choose more useful information to display in place of that column.

Describe the solution you'd like
The --format option allows you to display a single data item (--format=exe). That's fine, but it would be nice to be able to choose multiple values. Something like --format=tag,exe.

Describe alternatives you've considered
You can get this sort of report by piping --format=json into jq, or into a custom formatter, but that's fairly clumsy.

Additional context
Alternative to #86. The approach here is probably overkill, but I've filed it as an option in case changing the default format is unacceptable.

首先定位 py list 命令对 --format 的处理，并将其单项输出与现有的 JSON 输出进行比较。定义应如何解析和呈现逗号分隔的值（例如 tag,exe），然后验证多个选定字段是否按请求的顺序显示，同时不破坏现有的单值行为。