[Issue 5811][pulsar-client-python]Expose redelivery count of message …

…in python client (apache#5812)

Fixes apache#5811 

### Modifications

Added redelivery count method to message class

### Verifying this change

This change added tests and can be verified as follows:
  - Added python test for redelivery count

pulsar-client-cpp/python/pulsar/__init__.py

@@ -213,6 +213,12 @@ def topic_name(self):
         """
         return self._message.topic_name()
 
+    def redelivery_count(self):
+        """
+        Get the redelivery count for this message
+        """
+        return self._message.redelivery_count()
+
     @staticmethod
     def _wrap(_message):
         self = Message()

pulsar-client-cpp/python/pulsar_test.py

@@ -142,6 +142,29 @@ def test_producer_consumer(self):
         consumer.unsubscribe()
         client.close()
 
+    def test_redelivery_count(self):
+        client = Client(self.serviceUrl)
+        consumer = client.subscribe('my-python-topic-redelivery-count',
+                                    'my-sub',
+                                    consumer_type=ConsumerType.Shared,
+                                    negative_ack_redelivery_delay_ms=500)
+        producer = client.create_producer('my-python-topic-redelivery-count')
+        producer.send(b'hello')
+
+        redelivery_count = 0
+        for i in range(4):  
+            msg = consumer.receive(TM)
+            print("Received message %s" % msg.data())
+            consumer.negative_acknowledge(msg)
+            redelivery_count = msg.redelivery_count()
+
+        self.assertTrue(msg)
+        self.assertEqual(msg.data(), b'hello')
+        self.assertEqual(3, redelivery_count)
+        consumer.unsubscribe()
+        producer.close()
+        client.close()
+
     def test_consumer_initial_position(self):
         client = Client(self.serviceUrl)
         producer = client.create_producer('my-python-topic-producer-consumer')

pulsar-client-cpp/python/src/message.cc

@@ -138,6 +138,7 @@ void export_message() {
             .def("message_id", &Message_getMessageId, return_value_policy<copy_const_reference>())
             .def("__str__", &Message_str)
             .def("topic_name", &Topic_name_str)
+            .def("redelivery_count", &Message::getRedeliveryCount)
             ;
 
     MessageBatch& (MessageBatch::*MessageBatchParseFromString)(const std::string& payload, uint32_t batchSize) = &MessageBatch::parseFrom;