add method Destination.getName()

JMS topics and queues both have names that are accessible with getTopicName() and getQueueName(), but for applications where the type of destination (topic or queue) is configurable - which I would consider a good application - it's difficult to get the actual destination's name.

An ugly typecast or something similar must be used:

```
public static String getJMSDestinationName(Message msg) throws JMSException
{
Destination origDest = msg.getJMSDestination();
if( origDest==null ) return null;

if( origDest instanceof Topic) {
return ((Topic)origDest).getTopicName();
}
else {
return ((Queue)origDest).getQueueName();
}
}
```

What I'm proposing is simply a common Destination.getName() method so this code becomes nicer:

```
public static String getJMSDestinationName(Message msg) throws JMSException
{
return msg.getJMSDestination().getName();
}
```

The implementation of Destination.getName() is trivial for Topic and Queue.

I can understand the objection of saying: "'Destination' is just a marker interface and JMS abstracts from the actual topic/queue name, these names shouldn't matter."

But then, why is there getQueueName()/getTopicName() in the first place?

I find this name very useful in order to debug or sort message streams into buckets and it would be nice if this name will be simpler to get by.
#### Affected Versions
[2.0]

Start by reviewing the Destination, Topic, and Queue interfaces named in the issue, along with the six-comment discussion. Assess the proposed common name access against the existing type-specific methods; done requires a resolved API decision and corresponding changes for the affected messaging interfaces and implementations.

Written by the indexing model from the issue text.