Usage related changes

None, hopefully.

Development related changes

• Move integration tests into a separate crate tests/integration:
  • According to https://matklad.github.io/2021/02/27/delete-cargo-integration-tests.html
  • Modified the publishing shell script to skip that crate
• No more test modules within test files - all modules are in files of the same name.
• Faster test execution.
• Tests runnable simply with cargo test without the fear of too many CPUs overusing the memory.
  • This would resolve CI workflow sometimes overuses memory #378 if it hadn't already been marked as resolved.
• Close Unused import warnings #624
• Use --all-targets with clippy. Also use --workspace as replacement for the apparently deprecated --all.
• Add a cargo check to check parts of code not used by cargo build --release
• Remove unused bench
• Separate testing code from production code
  • In integration tests, not relying on features of other workspace crates, except for test_utils
• Use different BackgroundDevnet command depending on testing environment:
  • If local, same as it was
  • If CircleCI, rely on the pre-compiled binary.
• In BackgroundDevnet spawnng, extend max retries from 20 to 40 (10 seconds to 20).
• Replace crate netstat2 with listeners - otherwise doesn't compile on @marioiordanov's computer

Checklist:

• Checked out the contribution guidelines
• Applied formatting - ./scripts/format.sh
• No linter errors - ./scripts/clippy_check.sh
• No unused dependencies - ./scripts/check_unused_deps.sh
• No spelling errors - ./scripts/check_spelling.sh
• Performed code self-review
• Rebased to the latest commit of the target branch (or merged it into my branch)
  • Once you make the PR reviewable, please avoid force-pushing
• Updated the docs if needed - ./website/README.md
• Linked the issues resolvable by this PR - linking info
• Updated the tests if needed; all passing - execution info