add --no-aliases flag to not show aliases when using --list

[WJehee]

Hey there, this is my first contribution to this project, please let me know if any changes need to be made.

This PR aims to fix https://github.com/casey/just/issues/1891, since I came across the same problem. I implemented the completions files, but I wasn't able to test most of them, I use zsh myself but the completions did not seem to work, although I could see them when passing --completions=zsh, perhaps you know what the problem is?

[casey]

Looks good to me! This just needs a test.

[WJehee]

Added a test, I'm not sure if the standard is to create a new file for this but that is what I did

[casey]

Looks like there's an issue with formatting.

[casey]

Merged!