chronik-client-integration-tests is notorious for breaking (see D16077).
One way to remy this is to move the test logic from the python setup scripts into the functional tests themselves, without having to do any IPC within the test itself.
To do this, we import the new ecash-lib into the chronik-client integration tests (here, only chronik_info.ts), and interact only through chronik.
Similar to D16063, we split the type checking and the build step of TypeScript, but here we do it to resolve the circular dependency between chronik-client's tests and ecash-lib, which have to be built in this order to work: chronik-client (build:lib), then ecash-lib.
Mocha gives us Unknown file extension ".ts" for unclear reasons after this change; it is fixed by using the tsx package, like we've done for ecash-lib's tests already previously.