Introduce an IT for consistency

[wprzytula]

This PR introduces the first integration test for the CPP-Rust Driver that is written in Rust.

The test is based on an analogous one that is present in the Rust Driver. It finally convinces me that the consistencies are handled correctly.

Pre-review checklist

• I have split my patch into logically separate commits.
• All commit messages clearly explain what they change and why.
• PR description sums up the changes and reasons why they should be introduced.
• [] I have implemented Rust unit tests for the features/changes introduced.
• [] I have enabled appropriate tests in Makefile in {SCYLLA,CASSANDRA}_(NO_VALGRIND_)TEST_FILTER.
• [] I added appropriate Fixes: annotations to PR description.

[Copilot]

Pull Request Overview

This PR introduces a new Rust-based integration test for the C++/Rust driver wrapper that verifies consistency levels are applied correctly.

• Adds utility functions and test harness in tests/integration/utils.rs to run a 3-node dry-mode proxy cluster and inspect requests.
• Implements a comprehensive consistency_is_correctly_set_in_cql_requests test in tests/integration/consistency.rs.
• Adjusts visibility in argconv.rs and updates dev-dependencies to pull in scylla-cql and itertools.

Reviewed Changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tests/integration/utils.rs	Utilities for setting up a proxy cluster, error assertion macros, and request-forging helpers
tests/integration/main.rs	Registers the consistency and utils modules for integration tests
tests/integration/consistency.rs	New async integration test covering all consistency and serial-consistency settings
src/argconv.rs	Changed several internal pointer conversion/borrowing methods to pub
Cargo.toml	Added scylla-cql and itertools to dev-dependencies

Comments suppressed due to low confidence (2)

scylla-rust-wrapper/src/argconv.rs:9

• [nitpick] Exposing ptr_to_cstr as a public API may unnecessarily broaden your crate's surface area. Consider reverting it to pub(crate) unless external consumers genuinely need this function.

pub unsafe fn ptr_to_cstr(ptr: *const c_char) -> Option<&'static str> {

scylla-rust-wrapper/src/argconv.rs:13

• [nitpick] Similarly, ptr_to_cstr_n is an internal helper and could be kept pub(crate) to avoid exposing low-level unsafe conversions in your public API.

pub unsafe fn ptr_to_cstr_n(ptr: *const c_char, size: size_t) -> Option<&'static str> {

[wprzytula]

Rebased on master and appeased clippy.