[Feature] Zero-downtime full re-index of Elasticsearch

A common need while working with ES is to rebuild the index from scratch.

Let's take an example to highlight an issue. I have an index of Products. My products database moves a lot, for stock updates or creation of new products/disabling some others: it changes, a lot. I have 1 000 000 products in my database.
I want to rebuild my products index: this process will take a while, and in the meantime, I need to be consistent with updates on the new and the old index.

To stay consistent, it would be convenient if the IndexationRequest could update many indexes simultaneously, with an extra argument it would be possible. Something like this:

```php
$request = new IndexationRequest($document, ['indexes' => [
$liveIndex->getName(),
$newIndex->getName()
]);
```