As of Spring Data Moore, a new reactive template and the
corresponding repositories support have been added.

This commit auto-configures a `ReactiveElasticsearchTemplate`
with the configuration properties under the
`spring.data.elasticsearch.client.reactive` namespace.
To enable this feature, applications require both Spring Data
Elasticsearch dependencies (typically
`spring-boot-starter-data-elasticsearch`) and dependencies
for a `WebClient` (often `spring-boot-starter-webflux`).

The support for the reactive Elasticsearch repositories is
also provided.

Closes gh-16214