Add getActiveTopic method to RPatternTopicReactive & RPatternTopicRx

Signed-off-by: Shihao <327800885@qq.com>

redisson/src/main/java/org/redisson/api/RPatternTopicReactive.java

@@ -66,4 +66,11 @@ public interface RPatternTopicReactive {
      */
     Mono<Void> removeListener(int listenerId);
 
+
+    /**
+     * Returns  active topic list of this pattern
+     * @return all actives channel of this pattern
+     */
+    Mono<List<String>> getActiveTopics();
+
 }

redisson/src/main/java/org/redisson/api/RPatternTopicRx.java

@@ -66,4 +66,10 @@ public interface RPatternTopicRx {
      */
     void removeListener(int listenerId);
 
+    /**
+     * Returns active topic list of this pattern
+     * @return all actives topic of this pattern
+     */
+    Single<List<String>> getActiveTopics();
+
 }