Fix BasicRabbitService disconnection

- Disposing channel and connection objects is not enough. See https://www.rabbitmq.com/dotnet-api-guide.html#disconnecting
- It's generally not a good practice to lock on 'this' because code from other classes can potentially acquire a lock on the same object leading to deadlocks. Refactored to new object like what is used elsewhere in this project

SimpleRabbit.NetCore/Service/BasicRabbitService.cs

@@ -15,6 +15,7 @@ public interface IBasicRabbitService : IDisposable
 
     public abstract class BasicRabbitService : IBasicRabbitService
     {
+        private readonly object _lock = new object();
         private const ushort DefaultRequestedHeartBeat = 5;
         private const int DefaultNetworkRecoveryInterval = 10;
 
@@ -79,27 +80,29 @@ protected BasicRabbitService(RabbitConfiguration config)
 
         public IBasicProperties GetBasicProperties()
         {
-            lock(this)
+            lock (_lock)
             {
                 return Channel.CreateBasicProperties();
             }
         }
 
         public void ClearConnection()
         {
-            lock (this)
+            lock (_lock)
             {
                 if (_disposed)
                 {
                     return;
                 }
                 try
                 {
+                    _channel?.Close();
                     _channel?.Dispose();
                     _channel = null;
                 }
                 finally
                 {
+                    _connection?.Close();
                     _connection?.Dispose();
                     _connection = null;
                 }
@@ -109,7 +112,7 @@ public void ClearConnection()
 
         public void Close()
         {
-            lock (this)
+            lock (_lock)
             {
                 if (_disposed)
                 {