feat(libutil): implement hashing in zig

[RossComputerGuy]

Motivation

Fixes #11
Partial on #13

Context

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[RossComputerGuy]

zix-util-tests-run> [----------] 3 tests from BLAKE3HashTest
zix-util-tests-run> [ RUN      ] BLAKE3HashTest.testKnownBLAKE3Hashes1
zix-util-tests-run> nix-util-tests: ../hash.cc:433: std::string_view nix::printHashAlgo(HashAlgorithm): Assertion `false' failed.
zix-util-tests-run> /build/.attr-0l2nkwhif96f51f4amnlf414lhl4rv9vh8iffyp431v6s28gsr90: line 2:     7 Aborted                 (core dumped) /nix/store/lyd6j7s9dsdrhy6plpb30lfcj3v83wgb-execline-2.9.6.1-bin/bin/exec /nix/store/613xn221y5jbwp9m7vazvyph7hfx13mb-zix-util-tests-0.1.0pre/bin/nix-util-tests

Test fail