Improve ANSI white / light white output

[penelopeysm]

Closes #3593

Screenshots in light/dark mode:

Try this Pull Request!

Open Julia and type:

julia> import Pkg
julia> Pkg.activate(temp=true)
julia> Pkg.add(url="https://github.com/penelopeysm/Pluto.jl", rev="main")
julia> using Pluto

[penelopeysm]

This was being shadowed by the line below

[Pangoraw]

Thanks!

[fonsp]

Thank you, your changes are nice!

There are still some contrast issues in the other colors. Notably, the colors should be inverted in "light mode". ie in light mode, "White" should actually be black. I think the idea is that terminal color code is designed for a white-text-on-black-background terminal, and in light mode, you just invert everything.

Here is a screenshot from the MacOS terminal to show how to handle this properly:

EDIT: wait the MacOS app is not showing what I mean.

[fonsp]

Moved to #3623

[penelopeysm]

There are still some contrast issues

I'm aware, that's why I opened #3596 :)

[fonsp]

Ahh right! I thought I remembered it but I forgot you made a separate issue. Thank you!