Refactoring: vaccination

src/flask_covid19/blueprints/app_all/all_service_download.py

src/flask_covid19/blueprints/data_divi/divi_service.py

src/flask_covid19/blueprints/data_divi/divi_views.py

src/flask_covid19/blueprints/data_ecdc/ecdc_service.py

src/flask_covid19/blueprints/data_owid/owid_service.py

src/flask_covid19/blueprints/data_rki/rki_service.py

...ovid19/blueprints/data_vaccination/vaccination_service.py

src/flask_covid19/blueprints/data_who/who_service.py