test(fit): add score_time clock integration test

[clanghans]

What

Adds a feature integration test (FIT) for the score_time clock library.
score_time is already pinned in known_good.json (and the generated
bazel_common/score_modules_target_sw.MODULE.bazel), but so far it had no
integration test coverage. This adds one following the existing FIT pattern
(C++ scenario binary + pytest driver).

Scope

Three C++ scenarios exercise the public Clock<Tag> API and self-validate,
throwing (process exit 101) on failure:

• time.system_clock_now — SystemClock::Now() tracks the host system clock
  within a generous tolerance (catches an epoch-zero stub / unlinked backend).
• time.steady_clock_now — two SteadyClock::Now() readings are monotonic.
• time.high_res_steady_clock_now — HighResSteadyClock::Now() is non-zero and
  monotonic.

Each scenario emits its reading as a structured JSON log line. The pytest FIT
case (tests/time/test_clock_now.py) drives each scenario and asserts the exit
code plus the emitted reading. score_time is C++ only, so the tests are
parametrized with version=["cpp"].

Deferred (not in this PR): VehicleTime (requires explicit Init()), and the
time_daemon / time_slave / ts_client processes (better suited to ITF/QEMU tests).

Files

• feature_integration_tests/test_scenarios/cpp/src/scenarios/time/ — new scenarios + group mod.cpp
• feature_integration_tests/test_scenarios/cpp/src/internals/time/clock_log.h — small JSON log helper
• feature_integration_tests/test_scenarios/cpp/src/scenarios/mod.cpp — register the time group
• feature_integration_tests/test_scenarios/cpp/BUILD — add the three @score_time clock deps
• feature_integration_tests/test_cases/tests/time/test_clock_now.py — pytest FIT case

Verification

• bazel build --config=linux-x86_64 //feature_integration_tests/test_scenarios/cpp:cpp_test_scenarios — builds with the score_time deps.
• Ran each scenario binary directly — exit 0 with valid readings.
• bazel test --config=linux-x86_64 //feature_integration_tests/test_cases:fit_cpp — all tests pass (6 new time tests + existing suite).
• Python (ruff) and Starlark (buildifier) format checks pass.

[PiotrKorkus]

good for basic smoke tests

did you consider any feature reqs? could you add the mapping?

I would suggest adding a scenario where we do a couple of ticks in a loop, assert all are not decreasing, then sleep for some known duration and compare again next tick.

[PiotrKorkus]

redundant? should be possible to use FitScenario directly