Add GTK4

[ashbork]

Hi!
I managed to put together a libadwaita theme. The readme and releases will need to be updated if this PR gets merged, as I also changed the repo's structure according to @mvllow's recommendation. I'd be happy to help with that too.

[mvllow]

Unfortunately this is too large for me to review on both the web and local (both error out before I'm able to view anything). Maybe @ThatOneCalculator can chime in 😌

[ThatOneCalculator]

I'll have to test this out when I have the chance, thank you!

[ThatOneCalculator]

I'm looking at all the SVGs and everything on my phone, I've gotta say it looks like you did an incredible job! What did you use to make this @maybork ?

[ashbork]

If you mean the icons, they're the ones that are currently in the repo, I just moved them to keep it more organized, I wouldn't dare attributing them to myself! To be fair, that simple change does make it seem like I did a lot more than just moving files, sorry, I'm pretty new to Git.

Of course, the structure could be changed if you wish - I just thought that it'd be way easier to follow the installation steps with the files divided across directories, especially since GTK4 and libadwaita means that there's another step necessary if we want a consistent user experience. I'll leave that decision up to you, though!

As for the creation of the GTK4 theme, this was way easier through the build tool - otherwise, the process is just defining a bunch of colors. Replacing one's ~/.config/gtk-4.0/gtk.css with one of the variants overrides the default libadwaita colors - no need for Tweaks. However, legacy apps still need a GTK3 theme (and you need to apply them through Tweaks).

[ThatOneCalculator]

I keep trying to review it 😂

[ThatOneCalculator]

From my testing it works great, I'll merge it for now and lyk if any more issues arise. Thank you for your work on this!