Allow removeMembersFromConsumerGroup without members (#1227)

In the Kafka Admin API, it's possible to call
`removeMembersFromConsumerGroup` without passing any member. This is
different from passing an empty `Set()` which is failing the validation
of `RemoveMembersFromConsumerGroupOptions`.

zio-kafka/src/main/scala/zio/kafka/admin/AdminClient.scala

@@ -242,6 +242,11 @@ trait AdminClient {
    */
   def removeMembersFromConsumerGroup(groupId: String, membersToRemove: Set[String]): Task[Unit]
 
+  /**
+   * Remove all members from a consumer group.
+   */
+  def removeMembersFromConsumerGroup(groupId: String): Task[Unit]
+
   /**
    * Describe the log directories of the specified brokers
    */
@@ -756,6 +761,18 @@ object AdminClient {
       ).unit
     }
 
+    /**
+     * Remove all members from a consumer group.
+     */
+    override def removeMembersFromConsumerGroup(groupId: String): Task[Unit] = {
+      val options = new RemoveMembersFromConsumerGroupOptions()
+      fromKafkaFuture(
+        ZIO.attemptBlocking(
+          adminClient.removeMembersFromConsumerGroup(groupId, options).all()
+        )
+      ).unit
+    }
+
     override def describeLogDirs(
       brokersId: Iterable[Int]
     ): ZIO[Any, Throwable, Map[Int, Map[String, LogDirDescription]]] =