Add support for Darwin to convmv. This required disabling the tests as
APFS requires filenames to be valid UTF-8[^1]. This will also affect
Linux if a filesystem that enforces valid UTF-8 is used (such as ZFS
with `utf8only=on`).
While we're here, make some changes to clean up the derivation:
- Replace use of `rec` with `finalAttrs` pattern
- Replace `fetchurl` with `fetchzip`
- Added separate `man` output
- Replace `preBuild` hook with explicit `makeFlags` initialization
- Replace explicit `patchPhase` override with `prePatch` hook
- Enable `strictDeps`
- Disable redundant `patchShebangs` call (already done in `prePatch`
hook)
- Address lints from `nixpkgs-hammer`
- Reformat with `nixfmt-rfc-style`
- Migrate to pkgs/by-name
[^1]: https://developer.apple.com/library/archive/documentation/FileManagement/Conceptual/APFS_Guide/FAQ/FAQ.html
