Remove unsafe methods form swagger ui

Also add custom exception handling to the api, uniforming how failures
are reported to the consumer.
DRF ApiException and derived hold the failure message on a "detail" attribute, while we were using a "message" attribute for all the jobs-related endpoint. There are still a few cases where the "message" attribute is used but I want to be sure that there is no side effect on renaming those. @jeads do you know if thclient does some parsing of the response in case of errors?