Enable gzip compressed payload

[mobilemarines]

Hello,

Let me explain, we had the need to send a gzip compressed payload to our Backend. Before the switch to this plugin we used the angular http client and transmitted our gzipped payload in an ArrayBuffer Object. But unfortunately this object was emptied by the JSBridge (see: https://github.com/ionic-team/capacitor/issues/2273).

We wanted to keep the Backend Code, so we decided to adjust the Plugin to archive the same outcome.

Please tell us if it needs some improvement or if we can support. All libraries used are MIT licensed.