Refactoring: rename covid19 to flask_covid19

src/flask_covid19/blueprints/divi/divi_model.py

src/flask_covid19/blueprints/ecdc/ecdc_model.py

src/flask_covid19/blueprints/ecdc/ecdc_service.py

src/flask_covid19/blueprints/ecdc/ecdc_service_import.py

src/flask_covid19/blueprints/ecdc/ecdc_service_update.py

src/flask_covid19/blueprints/ecdc/ecdc_views.py

src/flask_covid19/blueprints/ecdc_test/ecdc_test_service.py

src/flask_covid19/blueprints/ecdc_test/ecdc_test_views.py

src/flask_covid19/blueprints/owid/owid_model.py

src/flask_covid19/blueprints/owid/owid_service.py

src/flask_covid19/blueprints/owid/owid_service_import.py

src/flask_covid19/blueprints/owid/owid_service_update.py

src/flask_covid19/blueprints/owid/owid_views.py

src/flask_covid19/blueprints/owid/owid_views_diagrams.py

src/flask_covid19/blueprints/owid_test/owid_test_service.py

src/flask_covid19/blueprints/owid_test/owid_test_views.py

src/flask_covid19/blueprints/rki_cases/rki_model.py

src/flask_covid19/blueprints/rki_cases/rki_service.py

src/flask_covid19/blueprints/rki_cases/rki_service_import.py

src/flask_covid19/blueprints/rki_cases/rki_service_update.py