Remove usage of `org.elasticsearch` classes from non-template classes

[sothawo]

We need to remove usages of org.elasticsearch classes. The only classes where we must actually keep this is in the concrete implementations of the (Reactive)ElasticsearchOperations classes.

Once the new Elasticsearch client is available, we will not be able to use theses classes anymore. For enums or callbacks we need to provide our own similar classes and provide a mapping in the *Template classes.

[sothawo]

2 parts are not resolved in this issue:

• suggest API
• aggregation results

These will be addressed in separate issue