Elasticsearch integration

[jmartisk]

Langchain4j supports an Elasticsearch embedding store. To properly integrate it with our quarkus-elasticsearch-rest extension, we will need a few changes upstream to allow passing a pre-created elasticsearch client.

I've been also thinking that maybe we could implement more stuff beyond the embedding store, maybe some kind of full-text content retriever based on Elasticsearch would make sense.

[geoand]

I think @yrodiere had some thoughts on this

[sebastienblanc]

Some related happen here https://github.com/quarkiverse/quarkus-langchain4j/pull/213