more validations for CoSERV `ResultSet`

[thomas-fossati]

Results for different artifact types are mutually exclusive. So these results should be invalid:

(RVQ != nil && (EVQ != nil || CEQ != nil)) ||
(RVQ != nil && (TAS !=nil || AKQ != nil)) ||
((AKQ != nil || TAS !=nil) && (EVQ != nil || CEQ != nil))

Another validation that can be added is checking SourceArtifacts are all cmw.KindMonad.

Originally posted by @DhanusML in #273 (comment)