Add RAII for cl_objects

- add removeVirtualEvent to cmdQueue fixture
- add const keyword in event functions

Change-Id: I11354eb8fceb15ae2c58bddd327863a15aab6393

unit_tests/utilities/base_object_utils.h

@@ -26,4 +26,9 @@ template <typename T>
 static ReleaseableObjectPtr<T> clUniquePtr(T *object) {
     return ReleaseableObjectPtr<T>{object};
 }
+
+template <class _Ty, class... _Types>
+inline ReleaseableObjectPtr<_Ty> make_releaseable(_Types &&... _Args) {
+    return (ReleaseableObjectPtr<_Ty>(new _Ty(std::forward<_Types>(_Args)...)));
+}
 } // namespace OCLRT