refactor!: re-implement iroha_test_network

[0x009922]

Context

Very early draft, work in progress!

iroha_test_network has a few problems:

• It doesn't test Iroha as a black box, but runs directly using internal implementation details.
• Execution flow of peers is messy, hard to debug & control. (e.g. for cases of restarts). Logs from all peers are all over the place, very noisy.
• Messy API: hard to fine tune the network & peers for specific cases; high coupling with defaults; thread::sleeps with pipeline time instead of providing precise lifecycle hooks
• Non-optimal defaults: most of the tests don't need 4 peers with 4s of pipeline time. A single peer with close-to-zero block time works significantly faster.

Black boxing would mean to run Iroha through its CLI as a dedicated process, just as users would do.

Solution

Re-implement iroha_test_network:

• Black-boxing: run irohad as a direct child process.
  • Create temp dir for every randomly generated peer and store there its state, configs, and logs. It could be observed (and maybe even replayed??) after tests run.
  • Configuration through raw TOML - feel your users!
  • Can work with any irohad target (e.g. debug, `release)
• Allocate ports automatically (fslock-based solution) - no more manual ports setting. Works intra-process (cargo tests) and inter-process (cargo nextest Use Nextest #4987).
• Higher-level, dynamic, flexible, async-first API, helpful for writing expressive tests.
• Optimal defaults: a single peer with very short timings.
• Faster!
• Bonus: test execution can now be terminated immediately with SIGINT (Ctrl + C). It used to be suspended.

Other changes:

• Turns out some integration tests were broken, but passing for other reasons. It was primarily a cause of a messy test network API.
• Make irohad a closed binary; don't expose Iroha; remove samples from it. Closes [suggestion] Refactor Iroha CLI #4136
• Minor changes in iroha_core and iroha_torii.
• remove unstable_network tests: they rely on a direct violation of black boxing - the use of FreezeStatus to make peers faulty. To be re-implemented in some other way.

Further steps

• [suggestion] Fully asynchronous client API #3130 is a must
• Make iroha_test_network an executable, use in pytests and in SDKs

Migration Guide (optional)

TODO

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Review notes (optional)

Due to Client still being blocking, there is some ugly code with spawn_blocking.

Checklist

• I've read CONTRIBUTING.md.
• (optional) I've written unit tests for the code changes.
• All review comments have been resolved.
• All CI checks pass.

Undraft:

• Update all integration tests
• Update benches and examples
• Support running from CI (set irohad binary path via ENV?)

[nxsaken]

Does this line relate to the imports below irohad?

[0x009922]

Tbh, I don't see how it was related to it before. Seemed an odd outdated comment for me.