GH-1339: Fix RLErrorHandler with Conversion Ex. (#1346)

Resolves https://github.com/spring-projects/spring-amqp/issues/1339

Error handler was not called for conversion exceptions, preventing
the application from returning some error to the caller for request/reply processing.

**cherry-pick to 2.2.x**

src/reference/asciidoc/amqp.adoc

@@ -3276,7 +3276,7 @@ static class TxServiceImpl implements TxService<Foo> {
 
     @Override
     @RabbitListener(...)
-    public String handle(Foo foo, String rk) {
+    public String handle(Thing thing, String rk) {
          ...
     }
 
@@ -3359,6 +3359,10 @@ public Object handleError(Message amqpMessage, org.springframework.messaging.Mes
 ----
 ====
 
+Starting with version 2.2.18, if a message conversion exception is thrown, the error handler will be called, with `null` in the `message` argument.
+This allows the application to send some result to the caller, indicating that a badly-formed message was received.
+Previously, such errors were thrown and handled by the container.
+
 ====== Container Management
 
 Containers created for annotations are not registered with the application context.