Added some utitlity functions and corresponding tests:
assure_entity_is_in_list for checking whether an entity has another
entity in one of its properties and possibly sets it
assure_has_parent checks whether an entity has a parent and possibly
adds it
insert_id_based_on_name and get_ids_for_entities_with_names for adding
ids to entities in a container such that they can be updated

Caution: Cfood do no longer take the match on creation but the CaosDB
File

Restructure CFood and Crawler

See merge request bmp-caosdb/caosdb-advanced-user-tools!6

fix gitlab ci by setting docker versions

See merge request bmp-caosdb/caosdb-advanced-user-tools!5

Integrationtest

See merge request bmp-caosdb/caosdb-advanced-user-tools!4