This upgrades the default version of zig to zig_0_12, which builds
reproducibly on darwin.
Fixes#299091.
Also upgrades all packages compatible with zig 0.12 to that version.
I tried to upgrade packages currently pinning 0.11 as well, but only a
few worked.
Co-authored-by: Weijia Wang (wegank) <contact@weijia.wang>
Also, a cosmetic refactor:
- Reorder parameter listing
- Use rec-less, overlay-style overridable recursive attributes (in effect since
NixOS#119942);
- Remove nested with (according to
https://nix.dev/recipes/best-practices#with-scopes)
