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.

先定位 py list 命令對 --format 的處理，並將其單項輸出與現有的 JSON 輸出進行比較。定義應如何解析和呈現逗號分隔的值（例如 tag,exe），然後驗證多個選取的欄位是否依要求的順序顯示，同時不破壞現有的單值行為。