Custom configuration for the Elasticsearch REST client in Hibernate Search

[yrodiere]

Description

See https://docs.jboss.org/hibernate/stable/search/reference/en-US/html_single/#backend-elasticsearch-configuration-http-client: Hibernate Search allows for plugging in a custom component to customize the Elasticsearch REST client.

We should expose that configuration in Quarkus.

Implementation ideas

We may want to expose this through annotations on CDI beans rather than a configuration property; see #24922 .

[quarkus-bot]

/cc @gsmet, @loicmathieu, @michalszynkiewicz

[yrodiere]

We might not need this at all if we address #26991: then developers will be able to use @ElasticsearchClientConfig.