This updates our bundled Harfbuzz from 8.4 to 11.0. The changes from 8
to 11 include a number of correctness and performance improvements.
Packaged releases tend to dynamically link so this won't affect
existing users, but build-from-source users hopefully get an
improvement.
We have always tracked a post-3.4 release, this brings us up to date.
There's no real motivation beyond this other than keeping up to date
since we're already on non-release versions anyways.
Upstream is now mostly pure Zig and the build.zig.zon.* files are
generated directly by zon2nix. The JSON file is no longer used as an
intermediate file but is retained for downstream packager usage.
