Pass cancellationToken to next() in pipeline behaviors

Updated the `Handle` method in multiple classes implementing
`IPipelineBehavior<SignCommand, Unit>` to pass the `cancellationToken`
parameter to the `next()` method. This change ensures consistent
propagation of the `cancellationToken` through the pipeline, enabling
proper handling of cancellation requests during asynchronous operations.

Modified files:
- AnnotationBehavior.cs
- DocStatusBehavior.cs
- HistoryBehavior.cs
- SendSignedMailBehavior.cs

EnvelopeGenerator.Application/Signatures/Behaviors/DocStatusBehavior.cs

@@ -45,6 +45,6 @@ public class DocStatusBehavior : IPipelineBehavior<SignCommand, Unit>
                         : BlankAnnotationJson
         }, cancellationToken);
 
-        return await next();
+        return await next(cancellationToken);
     }
 }