Bulk API should support documents encoded in JSON as well as encoded in SMILE

[iverase]

Currently the High Level Rest Client supports bulks API to send documents encoded either in JSON or SMILE as stated in the docs:

The Bulk API supports only documents encoded in JSON or SMILE. Providing documents in any other format will result in an error.

I think this client should support it as well.

It is important to note that this is not only a wire concern as it has implication in how Elasticsearch will store the documents. The format the documents are sent determines how they are stored in _source which it has implication in index size and performance when fetching fields.