Introduce a counting process as a test utility

[cameron-craig-etas]

#588

This PR introduces a "counting" process that optionally posts to a named semaphore, and also optionally report running. This is a useful testing utility for occasions where we would like to wait for a number of processes to be started.

I've tested this locally:

• Tested that the semaphore is created and posted to correctly:

  $ bazel build //tests/utils/test_helper:counting_process
  $ bazel-bin/tests/utils/test_helper/counting_process  -p /namedsem
  $ stat -c '%a %n' /dev/shm/sem.namedsem
  644 /dev/shm/sem.namedsem
  $ ./bin/python3 -c "import posix_ipc; sem = posix_ipc.Semaphore('/namedsem'); print('Value:', sem.value)"
  Value: 1
  $ bazel-bin/tests/utils/test_helper/counting_process  -p /namedsem
  Value: 2
  

• Tested that report_running is called when configured.

  bazel-bin/tests/utils/test_helper/counting_process -r
  mw::log initialization error: Error No logging configuration files could be found. occurred with context information: Failed to load configuration files. Fallback to console logging.
  2026/09/03 11:38:32.1912871 130631703 000 ECU1 NONE LM log error verbose 3 [Lifecycle client] FD  111  is invalid for kRunning report
  

• Tested that the help option works:

  $ bazel-bin/tests/utils/test_helper/counting_process --help
  Usage: ./counting_process [--help|-h] [--report-running|-r] [--post-to-semaphore|-p]
  $ bazel-bin/tests/utils/test_helper/counting_process -h
  Usage: ./counting_process [--help|-h] [--report-running|-r] [--post-to-semaphore|-p]
  

• Tested that an error is printed if no arguments are passed.

  $ bazel-bin/tests/utils/test_helper/counting_process
  Invalid arguments! Must provide at least one option.
  

• Tested that invalid or missing arguments are handled:

  $ bazel-bin/tests/utils/test_helper/counting_process -j
  bazel-bin/tests/utils/test_helper/counting_process: invalid option -- 'j'
  Invalid or missing argument.
  $ bazel-bin/tests/utils/test_helper/counting_process -p
  bazel-bin/tests/utils/test_helper/counting_process: option requires an argument -- 'p'
  Invalid or missing argument.
  

• Test that invalid sem names are rejected

  $ bazel-bin/tests/utils/test_helper/counting_process -p sem
  Invalid semaphore name! POSIX named semaphores must start with '/'