ReloadAnalyzersResponse missing streaming serialization #44383
Description
The new ReloadAnalyzersResponse class, which is returned by the _reload_search_analzyers api, does not implement Writeable or Streamable methods. This means if the response is serialized to another node, the information in the concrete class will be lost (the base class BroadcastResponse would still be deserialized).
Broadcast actions are handled by the coordinating node, and since all nodes can be coordinating, this does not affect the rest layer since the response will be built and immediately serialized to xcontent. However, in 7.x the transport client still exists, where this response would be serialized back to the client, and the reloadDetails would be lost.