Fixed cycle dependency (#6959)

ngraph/core/include/ngraph/op/util/variable.hpp

@@ -4,9 +4,13 @@
 
 #pragma once
 
-#include <ngraph/node.hpp>
+#include <string>
 #include <utility>
 
+#include "ngraph/partial_shape.hpp"
+#include "ngraph/type.hpp"
+#include "ngraph/type/element_type.hpp"
+
 namespace ngraph
 {
     struct VariableInfo

ngraph/core/include/ngraph/op/util/variable_context.hpp

@@ -4,6 +4,9 @@
 
 #pragma once
 
+#include <memory>
+#include <unordered_map>
+
 #include <ngraph/output_vector.hpp>
 #include <ngraph/variant.hpp>
 #include "ngraph/op/util/variable.hpp"

ngraph/core/include/ngraph/runtime/host_tensor.hpp

@@ -6,7 +6,7 @@
 
 #include <memory>
 
-#include "ngraph/node.hpp"
+#include "ngraph/descriptor/output.hpp"
 #include "ngraph/runtime/tensor.hpp"
 #include "ngraph/type/element_type.hpp"
 #include "ngraph/type/element_type_traits.hpp"