Add indent guides

[sudormrfbin]

Adds a theme scope ui.virtual.indent-guide.

TODO

• Guides for the last line is not rendered

[CptPotato]

Would it make sense to allow configuring which character to use as indent guide?
I see dotted ⋮ or dashed ┆ lines as possible alternatives.

[sudormrfbin]

Would it make sense to allow configuring which character to use as indent guide? I see dotted ⋮ or dashed ┆ lines as possible alternatives.

Yup, it should also be possible to disable it altogether, I'm planning to follow this up with a configuration PR.

[archseer]

I'm planning to follow this up with a configuration PR.

Can we add this here? I find indent guides distracting so I'd turn them off by default.

[sudormrfbin]

Indent guides are now configurable (off by default):

[editor.indent-guides]
render = true
character = "╎"

When both whitespace and indent guides are enabled, indent guides currently take precedence and display over visible whitespace (this mostly affects leading space characters):

Indent guides only	Visible whitespace only	Indent guides & visible whitespace together

[the-mikedavis]

I gave this a try locally and it looks great 🚀

The only thing I see that could be surprising is that the indent guides draw over tab characters if you have visible whitespace turned on. I think it makes sense for the indent guide to win in that case but we could re-think the rendering of tab in the future to offset by one column so it's visible or something similar.

[sudormrfbin]

Properly addressing that issue would have been easier if we were not limited to fixed width fonts. VSCode for example squeezes both the tab character and indent guide character into the same column by adjusting their sizes as required.

[archseer]

Looks great! No complaints