[message] add destructors for MessageQueue and PriorityQueue (#11550)

This commit adds destructors for `MessageQueue` and `PriorityQueue`.
This ensures that allocated `Message` instances in different queues
are freed when the `ot::Instance` is destroyed.

src/core/common/message.hpp

@@ -1569,7 +1569,7 @@ private:
 /**
  * Implements a message queue.
  */
-class MessageQueue : public otMessageQueue
+class MessageQueue : public otMessageQueue, private NonCopyable
 {
     friend class Message;
     friend class PriorityQueue;
@@ -1592,6 +1592,13 @@ public:
      */
     MessageQueue(void) { SetTail(nullptr); }
 
+#if OPENTHREAD_PLATFORM_NEXUS
+    /**
+     * Destructor of `MessageQueue`.
+     */
+    ~MessageQueue(void) { DequeueAndFreeAll(); }
+#endif
+
     /**
      * Returns a pointer to the first message.
      *
@@ -1678,7 +1685,7 @@ private:
 /**
  * Implements a priority queue.
  */
-class PriorityQueue : private Clearable<PriorityQueue>
+class PriorityQueue : private Clearable<PriorityQueue>, private NonCopyable
 {
     friend class Message;
     friend class MessageQueue;
@@ -1693,6 +1700,13 @@ public:
      */
     PriorityQueue(void) { Clear(); }
 
+#if OPENTHREAD_PLATFORM_NEXUS
+    /**
+     * Destructor of `PriorityQueue`.
+     */
+    ~PriorityQueue(void) { DequeueAndFreeAll(); }
+#endif
+
     /**
      * Returns a pointer to the first message.
      *