Add missing forward declaration

Author: MichaelElmore1

CSAPI-lib/DataModels/ControlStream.h

@@ -17,6 +17,9 @@
 #include "Component/DataComponentRegistry.h"
 
 namespace ConnectedSystemsAPI::DataModels {
+	class ControlStream;
+	void to_json(nlohmann::ordered_json& j, const ControlStream& v);
+
 	class ControlStream {
 	private:
 		std::optional<std::string> id;

CSAPI-lib/DataModels/ControlledProperty.h

@@ -7,6 +7,9 @@
 #include <nlohmann/json_fwd.hpp>
 
 namespace ConnectedSystemsAPI::DataModels {
+	class ControlledProperty;
+	void to_json(nlohmann::ordered_json& j, const ControlledProperty& v);
+
 	class ControlledProperty {
 	private:
 		std::optional<std::string> definition;

CSAPI-lib/DataModels/ObservedProperty.h

@@ -7,6 +7,9 @@
 #include <nlohmann/json_fwd.hpp>
 
 namespace ConnectedSystemsAPI::DataModels {
+	class ObservedProperty;
+	void to_json(nlohmann::ordered_json& j, const ObservedProperty& v);
+
 	class ObservedProperty {
 	private:
 		std::optional<std::string> definition;

CSAPI-lib/DataModels/TimeExtent.h

@@ -11,6 +11,9 @@
 #include "TimeUtils.h"
 
 namespace ConnectedSystemsAPI::DataModels {
+	class TimeExtent;
+	void to_json(nlohmann::ordered_json& j, const TimeExtent& v);
+
 	/// <summary>
 	/// Represents a time or time range.
 	/// Also supports special cases of time instants at 'now',