TMSS-272: Use RefResolver to use local refernce to common part, pointing, of the tmss schema

LCS/PyCommon/json_utils.py

SAS/TMSS/src/tmss/tmssapp/adapters/parset.py

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

SAS/TMSS/src/tmss/tmssapp/schemas/base.json

.../tmss/tmssapp/schemas/task-observation-with-stations.json

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

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

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

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

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

SAS/TMSS/test/t_parset_adapter.py

SAS/TMSS/test/tmss_test_data_django_models.py

SAS/TMSS/test/tmss_test_data_rest.py