Async: add sh_ptr<ContinuationChainLink> to Callback<>

This change enables us to finally implement the tracing of
continuations backward from the point of acquisition for deadlock
debugging.

smocore/include/body/body.h

@@ -3,6 +3,7 @@
 
 #include <component.h>
 #include <functional>
+#include <callback.h>
 
 namespace smo {
 
@@ -19,8 +20,8 @@ public:
 	~Body() = default;
 
 	typedef std::function<void(bool)> bodyLifetimeMgmtOpCbFn;
-	void initializeReq(bodyLifetimeMgmtOpCbFn callback);
-	void finalizeReq(bodyLifetimeMgmtOpCbFn callback);
+	void initializeReq(Callback<bodyLifetimeMgmtOpCbFn> callback);
+	void finalizeReq(Callback<bodyLifetimeMgmtOpCbFn> callback);
 
 private:
 	class InitializeReq;