RepositoryService: Make changes to how file-based subresoruces are mapped
CompositeResource: Define RESOURCE_NAMESPACE if we have not yet defined it...
RepositoryService: Add DomainTopic to CompositeDTOMapper with its fields. Part of #35922
RepositoryService: Update ReportUnit class to handle resources field separately to hide behind the scenes mapping. Fixes #35912
Merge branch 'CompositeMapping_Bug35912'