Merge remote-tracking branch 'origin/feat/create_variant' into feat/c…

…reate_variant

# Conflicts:
#	src/antares/model/study.py
#	src/antares/service/api_services/study_api.py
#	src/antares/service/base_services.py
#	src/antares/service/local_services/study_local.py
#	tests/antares/services/api_services/test_study_api.py