TMSS-206: added integration test for the subtask scheduling service

SAS/TMSS/services/subtask_scheduling/CMakeLists.txt

...MSS/services/subtask_scheduling/lib/subtask_scheduling.py

SAS/TMSS/services/subtask_scheduling/test/CMakeLists.txt

...s/subtask_scheduling/test/t_subtask_scheduling_service.py

.../subtask_scheduling/test/t_subtask_scheduling_service.run

...s/subtask_scheduling/test/t_subtask_scheduling_service.sh

SAS/TMSS/src/tmss/tmssapp/subtasks.py

SAS/TMSS/src/tmss/tmssapp/viewsets/scheduling.py

SAS/TMSS/test/tmss_test_data_rest.py