[chronik] Add test runner to bitcoinsuite-chronik-client

Summary:
Every Rust test that will trigger a child Python IPC test will use the test runner to execute, and to handle stderr / stdout.
The test runner takes in a script (to run the child Python IPC test) and a bespoke socket, giving the opportunity to run multiple
tests at once without worrying about socket collision.

This diff ensures sockets are passed to the child process correctly, setting up for future IPC communication.

Test Plan: cd modules/bitcoinsuite-chronik-client && cargo test -- --nocapture

Reviewers: O1 Bitcoin ABC, #bitcoin_abc, Fabien

Reviewed By: O1 Bitcoin ABC, #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D17564