Fix build and test on docs/installation.md and CONTRIBUTING.md

[lepapareil]

Fix PR #3281 comment

[jcamiel]

Hi @lepapareil

Not fan of the changes: we should really emphasize that Hurl is a "classic" Rust project and, as expected, build is straightforward:

• git clone ...
• cargo build

And that's all: cargo build to build, cargo test to unit test, cargo fmt to format and cargo clippy to lint. These are expected and well known commands to Rust developers, that works on every OS.

On the order, I would keep unit tests first then integration tests: the former don't need a live server and you can cargo test --lib just after cloning the repo without any Python stuff. The latter is more complicated and could just be run in the CI/CD.

Maybe we can add a last section to indicate that we have standalone scripts for each test if developers prefer: 'bin/build/test-unit.sh` for unit test etc... BTW, I don't remember if the build script is in debug or release but release build are way slower than debug build.

[lepapareil]

Got it