Add default visibility to class LegacyOpExtension (#14220)

* Add default visibility to class LegacyOpExtension

* Implement destructor in class LegacyOpExtension

src/core/dev_api/legacy_op_extension.hpp

@@ -9,5 +9,8 @@
 namespace ov {
 
 /** @brief Class to distinguish legacy extension. */
-class LegacyOpExtension : public BaseOpExtension {};
+class OPENVINO_API LegacyOpExtension : public BaseOpExtension {
+public:
+    ~LegacyOpExtension() override;
+};
 }  // namespace ov

src/core/src/legacy_op_extension.cpp

@@ -0,0 +1,7 @@
+// Copyright (C) 2018-2022 Intel Corporation
+// SPDX-License-Identifier: Apache-2.0
+//
+
+#include "legacy_op_extension.hpp"
+
+ov::LegacyOpExtension::~LegacyOpExtension() = default;