[WIP] Delete all records matching a query

Sorry, I'm having a bit of trouble digging through the code.

I think that this basic structure is correct for adding this functionality, but I'm unsure what to write in the `update_delete_all` method. Should it update some flag in the `request_options` `hash_storage`?

After that, where is the code that actually sends the request to ES? Will need to have it check for the new delete flag and send a DELETE request if it is true.
It is written here it need a `query` section for delete by query. And for this case there should be a filtered query, with type_name, but it should work automatically. Like I'm calling CitiesIndex::City.delete_all - it should include type filter already. And for CitiesIndex.delete_all - it should include `query: {}`, I suppose.