Refactoring: rename covid19 to flask_covid19

src/flask_covid19/__init__.py

src/flask_covid19/blueprints/app_admin/app_admin_views.py

src/flask_covid19/blueprints/app_all/all_service.py

src/flask_covid19/blueprints/app_all/all_service_config.py

src/flask_covid19/blueprints/app_all/all_service_download.py

src/flask_covid19/blueprints/app_all/all_services.py

src/flask_covid19/blueprints/app_all/all_views.py

...k_covid19/blueprints/app_application/application_views.py

src/flask_covid19/blueprints/who/who_model.py

src/flask_covid19/blueprints/who/who_model_import.py

src/flask_covid19/blueprints/who/who_service.py

src/flask_covid19/blueprints/who/who_service_import.py

src/flask_covid19/blueprints/who/who_service_update.py

src/flask_covid19/blueprints/who/who_views.py