fix(user fields): missing creationDate in details (#9250)

# Which Problems Are Solved

The `creationDate` property on user search V2 endpoint was missing

# How the Problems Are Solved

Added property in v2 `object.proto` and in the function creating the
details on each call

# Additional Changes
- none
# Additional Context
closes #8552

---------

Co-authored-by: Stefan Benz <46600784+stebenz@users.noreply.github.com>

internal/api/grpc/object/v2/converter.go

@@ -20,6 +20,9 @@ func DomainToDetailsPb(objectDetail *domain.ObjectDetails) *object.Details {
 	if !objectDetail.EventDate.IsZero() {
 		details.ChangeDate = timestamppb.New(objectDetail.EventDate)
 	}
+	if !objectDetail.CreationDate.IsZero() {
+		details.CreationDate = timestamppb.New(objectDetail.CreationDate)
+	}
 	return details
 }