ENH: add the 'add_prefix' argument

CHANGELOG.md

...ts/test_data/extroot/realworld_example/dataset_cfoods.yml

...ta/extroot/realworld_example/schema/dataspace.schema.json

integrationtests/test_realworld_example.py

integrationtests/test_use_case_simple_presentation.py

src/caoscrawler/crawl.py

unittests/test_tool.py