Check whether includes_advisories exists before accessing

[BenjaminPelletier]

report.json is not attached because
Relevant stacktrace:

Traceback (most recent call last):
  File "/app/monitoring/monitoring/uss_qualifier/suites/suite.py", line 150, in _run_test_scenario
    scenario.run(context)
  File "/app/monitoring/monitoring/uss_qualifier/scenarios/astm/utm/nominal_planning/conflict_equal_priority_not_permitted/conflict_equal_priority_not_permitted.py", line 186, in run
    _ = self._attempt_plan_flight_conflict()
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/monitoring/monitoring/uss_qualifier/scenarios/astm/utm/nominal_planning/conflict_equal_priority_not_permitted/conflict_equal_priority_not_permitted.py", line 210, in _attempt_plan_flight_conflict
    with OpIntentValidator(
  File "/app/monitoring/monitoring/uss_qualifier/scenarios/astm/utm/test_steps.py", line 93, in __exit__
    raise exc_val
  File "/app/monitoring/monitoring/uss_qualifier/scenarios/astm/utm/nominal_planning/conflict_equal_priority_not_permitted/conflict_equal_priority_not_permitted.py", line 218, in _attempt_plan_flight_conflict
    _, self.flight2_id, _ = plan_flight_intent(
                            ^^^^^^^^^^^^^^^^^^^
  File "/app/monitoring/monitoring/uss_qualifier/scenarios/flight_planning/test_steps.py", line 67, in plan_flight_intent
    resp, flight_id, advisories = submit_flight_intent(
                                  ^^^^^^^^^^^^^^^^^^^^^
  File "/app/monitoring/monitoring/uss_qualifier/scenarios/flight_planning/test_steps.py", line 247, in submit_flight_intent
    resp, query, flight_id, advisories = flight_planner.request_flight(
                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/monitoring/monitoring/uss_qualifier/resources/flight_planning/flight_planner.py", line 172, in request_flight
    resp = self.client.try_plan_flight(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/monitoring/monitoring/monitorlib/clients/flight_planning/client_v1.py", line 107, in try_plan_flight
    return self._inject(
           ^^^^^^^^^^^^^
  File "/app/monitoring/monitoring/monitorlib/clients/flight_planning/client_v1.py", line 96, in _inject
    includes_advisories=resp.includes_advisories,
                        ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/uss_qualifier_venv/lib/python3.11/site-packages/implicitdict/__init__.py", line 155, in __getattribute__
    return self[item]
           ~~~~^^^^^^
KeyError: 'includes_advisories'

Test check
N/A; uss_qualifier crashes

Difference from expected behavior
includes_advisories is an optional field in the flight_planning API and is rendered to an Optional field in the API object, but #422 accesses the field without checking if it is present. We need to check if the field is present before accessing it.