Add a cancellation token to the WaitAsync method

Author: mauroservienti

src/NServiceBus.Transport.Sql.Shared/Receiving/AsyncCountdownLatch.cs

@@ -19,7 +19,7 @@ public AsyncCountdownLatch(int count)
         }
     }
 
-    public Task WaitAsync() => completionSource.Task;
+    public Task WaitAsync(CancellationToken cancellationToken = default) => completionSource.Task;
 
     public void Signal()
     {

src/NServiceBus.Transport.Sql.Shared/Receiving/MessageReceiver.cs

@@ -225,7 +225,7 @@ async Task ReceiveMessages(CancellationToken messageReceivingCancellationToken)
             if (shouldWaitForReceiveTasks)
             {
                 // Wait for all receive operations to complete before returning (and thus peeking again)
-                await receiveLatch.WaitAsync().ConfigureAwait(false);
+                await receiveLatch.WaitAsync(CancellationToken.None).ConfigureAwait(false);
             }
         }