refactor(cargo-cp-artifact): use copyArtifact from @neon-rs/artifact

[dherman]

Closes #1045.

[kjvalencik]

cargo-cp-artifact currently has zero dependencies. I'm not sure if adding one for ~20 LoC is worth it.

[dherman]

cargo-cp-artifact currently has zero dependencies. I'm not sure if adding one for ~20 LoC is worth it.

It's an internal dependency, though: we maintain all the code. It's just that we use it in two different CLI tools, so it avoids us having to maintain it in two places.

[kjvalencik]

Given that we are likely to stop maintaining cargo-cp-artifact, my preference is not to couple the two and potentially make the neon CLI more difficult to maintain.