Support asStream to bypass decompression of gzipped responses

[thomasneirynck]

🚀 Feature Proposal

The Elasticsearch vector tile search API returns tiles, a binary response format. These can be gzipped (setting Accept-encoding: gzip, to even further reduce the response size.

Ideally, the JS-client does not decompress the tile, but allows a client to just get the gzipped return.

Motivation

Most web-clients that understand the vector-tile format (e.g. mapbox-gl), can use gzipped tiles transparently. There is no need to unzip in intermediate step and increase latency.

Example

Kibana Maps requests tiles from Elasticsearch. Rather than the JS-client unzipping and Kibana returning an unzipped response, Kibana could proxy the gzipped-tiles straight to the browser.

cc @delvedor @iverase