Add support for different strategies when generating RPC topics.

Source/MQTTnet.Extensions.Rpc/Options/TopicGeneration/DefaultMqttRpcClientTopicGenerationStrategy.cs

@@ -0,0 +1,20 @@
+using MQTTnet.Extensions.Rpc.Options.TopicGeneration;
+using System;
+
+namespace MQTTnet.Extensions.Rpc.Options
+{
+    public class DefaultMqttRpcClientTopicGenerationStrategy : IMqttRpcClientTopicGenerationStrategy
+    {
+        public MqttRpcTopicPair CreateRpcTopics(TopicGenerationContext context)
+        {
+            var requestTopic = $"MQTTnet.RPC/{Guid.NewGuid():N}/{context.MethodName}";
+            var responseTopic = requestTopic + "/response";
+
+            return new MqttRpcTopicPair
+            {
+                RequestTopic = requestTopic,
+                ResponseTopic = responseTopic
+            };
+        }
+    }
+}

Source/MQTTnet.Extensions.Rpc/Options/TopicGeneration/IMqttRpcClientTopicGenerationStrategy.cs

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+namespace MQTTnet.Extensions.Rpc.Options.TopicGeneration
+{
+    public interface IMqttRpcClientTopicGenerationStrategy
+    {
+        MqttRpcTopicPair CreateRpcTopics(TopicGenerationContext context);
+    }
+}

Source/MQTTnet.Extensions.Rpc/Options/TopicGeneration/TopicGenerationContext.cs

@@ -0,0 +1,16 @@
+using MQTTnet.Client;
+using MQTTnet.Protocol;
+
+namespace MQTTnet.Extensions.Rpc.Options.TopicGeneration
+{
+    public class TopicGenerationContext
+    {
+        public string MethodName { get; set; }
+
+        public MqttQualityOfServiceLevel QualityOfServiceLevel { get; set; }
+
+        public IMqttClient MqttClient { get; set; }
+
+        public IMqttRpcClientOptions Options { get; set; }
+    }
+}