deleting artifacts with archived artifacts is not possible

[antgonza]

We should add the possibility of deleting preps with archived artifacts - this occurs in cases like when we have a woltka 0.1.2 artifact, we archive it (so we don't delete and we can comparet it) to a newer version, i.e. woltka 0.1.2.

Anyway, I just did this by hand and the steps were - note that it might be worth changing the order of the commands:

qiita=> DELETE FROM  qiita.artifact_filepath where artifact_id in (select artifact_id from qiita.preparation_artifact where prep_template_id = XXXX);
DELETE XX

qiita=> delete from qiita.preparation_artifact where prep_template_id = XXXX;
DELETE XX

qiita=> delete  FROM  qiita.study_artifact where artifact_id in (XXXX,XXXX,XXXX);
DELETE XX

qiita=> delete  FROM  qiita.artifact where artifact_id in (XXXX,XXXX,XXXX);
DELETE XX