Custom CFFI based diagonal separator

[LordMZTE]

I've made a CFFI-module that acts as a 45-degree separator between modules. I've previously used a custom/... module with text set to " █", but this had several disadvantages:

• For some reason, I'd get tiny gaps between those characters
• It only looks right when the bar is the exact same height as the text, which I could only get working with negative padding in CSS
• When the background color of an adjacent module would change, for example due to the module entering a warning state (which even works with animations now and theoretically with all backgrounds you can do in CSS, gradients included... but no guarantees), the separator would stay the same color, breaking the illusion of the module being a parallelogram.
• The angle wasn't quite steep enough for my taste.

This thing currently lives in my dotfiles. Here's the code: https://git.mzte.de/LordMZTE/dotfiles/src/commit/631339f9dd9f09e0b37aa96b694ddd65003eb426/plugins/mzte-waybar/src/separator.zig

It's far from production-ready. It only works with horizontal bars, the angle isn't configurable and it doesn't hide itself when the module hides (definitely possible, though, but annoying since the next separator would have to adopt the color of the module a few places over), but perhaps someone could pick up from here 😉

(Also the way it draws the background of adjacent modules is very cursed API abuse... Not stable at all lol)

[LordMZTE]

I made the transition be a little nicer than a straight line, now it's got those spikes on it similar to my logo.