Replace empty CBRN CaseMetadata and DataFileMetadata elements

[cdmgtri]

CBRN defines two metadata elements, cbrn:CaseMetadata and cbrn:DataFileMetadata, which are both of type structures:MetadataType. This type is meant to be used as a parent type and not the type of a property, and the NDR is being updated accordingly for 6.0.

• cbrn:CaseMetadata (structures:MetadataType) is contained under type cbrn:CBRNECaseType
• cbrn:DataFileMetadata (structures:MetadataType) is contained under type cbrn:DataFileType

Recommendation options:

1. Change the types of these properties from structures:MetadataType to nc:MetadataType, or
2. Remove these custom properties since they do not have any specialized content and replace where they are currently being used with property nc:Metadata

[cdmgtri]

Harmonization Subcommittee recommends changing the type to nc:MetadataType.

[cdmgtri]

Merged into the dev branch for 6.0.