framework/output: Fix checking artifact kind
framework/output: Fix checking artifact kind

Don't construct an ArtifactType in Output.Add_artifact, the Artifact
class does that for us.

Next, fix the use of a nonexistent attribute Artifact.valid_kinds

lisatn/workload-automation,lisatn/workload-automation,ARM-software/workload-automation,setrofim/workload-automation,lisatn/workload-automation,ARM-software/workload-automation,setrofim/workload-automation,ARM-software/workload-automation,setrofim/workload-automation,lisatn/workload-automation,setrofim/workload-automation,ARM-software/workload-automation