Fix and improve the nix flake

[haraldh]

• fix(flake): public assets were moved to kitsune/assets

• feat(flake): use mold linker

• fix(flake): fix build dependency for openssl Native deps need the tools which run on the build host (when cross compiling). Normal build deps are the libs linked to the binary.

  OPENSSL_NO_VENDOR ensures that openssl-sys uses the system lib.

  Remove the rest of the workarounds for openssl.

• fix(flake): proper mkYarnPackage

• feat(flake): add overlay test to test overlay.nix

• fix(flake): skip more tests

• feat(flake): use the crane nix lib https://crane.dev/

  enables caching of artifacts and potentially reducing build time.

  Even End to End(E2E) testing could be added: https://crane.dev/examples/end-to-end-testing.html

• ci(flake): add nix github action

[haraldh]

Want me to disable cargo test in the "Nix checks" action (nix build)? There is a cargo nextest already, and you probably don't want to edit flake.nix constantly to disable tests, which need docker

[aumetra]

Yeah, I think testing inside the nix build isn't really needed since we have our CI to ensure buildability.

[haraldh]

Done as a separate commit, so it is easy to revert.

[aumetra]

Thank you for introducing the crane library, I saw a bit about it but never really looked into it too much.
About the Nix build though, is it doing a full release build? The timings seem like it. Can we downgrade that to a debug build in CI maybe?

[haraldh]

I had a misconfig in the crane calls, so it did not use the cached dependency build... Fixed that. Additionally the last commit changes the default to the dev profile, which is the debug mode. This although populates the github cache with lots more payload, because the debug artifacts are way bigger.

[haraldh]

Don't know why the build has failed.. no logs available. Maybe it ran out of RAM??

[aumetra]

Just gonna rerun it, maybe it works now? If not, then I'll have a look.
Yeah, I'd assume either RAM or disk space. Either way it's not good. I really need to start profiling the compilation and figure out where all the RAM is going

[haraldh]

I had to change the nix build TMPDIR for my system, because it builds in /tmp and this is a tmpfs

[haraldh]

kitsune-cli> installing /build/source/target/debug/kitsune-cli
kitsune-cli> cp: error copying '/build/source/target/debug/kitsune-cli' to '/nix/store/yjnadx1arhqmg9yj4y955w8ar3x8hnyr-kitsune-cli-0.0.1-pre.6/bin/kitsune-cli': No space left on device
error (ignored): error: cannot unlink '/tmp/nix-build-kitsune-0.0.1-pre.6.drv-0/source/target/debug/deps': Directory not empty
error: writing to file: No space left on device

Seems like a 2 debug builds in parallel is too big :)

[aumetra]

Thank you for working on this! This looks really good