workflows: decide what constraints to use

[gsrohde]

• [ ] Decide what constraints to use

For now, these constraints will be added:

ALTER TABLE workflows ALTER COLUMN folder SET NOT NULL;
ALTER TABLE workflows ADD CHECK (is_whitespace_normalized(folder));
ALTER TABLE workflows ALTER COLUMN hostname SET NOT NULL;
ALTER TABLE workflows ADD CHECK (is_whitespace_normalized(hostname));
ALTER TABLE workflows ALTER COLUMN params SET NOT NULL;
ALTER TABLE workflows ADD CHECK (is_whitespace_normalized(params));
ALTER TABLE workflows ALTER COLUMN advanced_edit SET NOT NULL;