[feature request] Support Consumer.getLastMessageId

First off, thank you for all the development you do on Pulsar! :smile:

### Motivation

When combining data from two Consumers by event timestamps and the topics have significant backlog, it gets tricky to make sure that all relevant events have arrived. If we could check from the Consumer whether we have already read the latest message, that would simplify the code.

The C++ client already supports Consumer.getLastMessageIdAsync. (Though the Java client has deprecated the singular version of that method, supposedly due to the Consumers being able to subscribe to several topics concurrently. For us right now the singular version is enough.)

Commencez par inspecter la Consumer API dans le dépôt pulsar-client-node ainsi que la prise en charge existante de getLastMessageIdAsync dans le client C++. Ajoutez ensuite la méthode Consumer demandée pour le client Node, puis vérifiez qu’elle indique si le dernier message a été lu, avec notamment une couverture pour les consommateurs ayant un retard important.

Rédigé par le modèle d'indexation à partir du texte de l'issue.