Migrate from make to meson

I don't think there's a lot to say here. Meson would probably be more comfortable for developers new to fd.o, and it would open up the ability to more easily integrate other languages with xdg-utils, such as C (something I'm particularly interested in, as the current scripts are Not Great, and could do better in adopting newer desktop standards, like xdg-desktop-portal support).

I've been losing my mind over this for (at the time of writing) the last hour, and I expect many more to be spent on this. Having someone with more knowledge in how the current build system works working on this would be amazing.