Add support for compression

[espenhogbakk]

There seems to be no support for compressing the data transferred between server and client. I had a look at the internals and i see there are some flags in the internalConfig for compression that defaults to false. I tried enabling it but seems there is no decompression implemented.

Would be really nice if compression could be added as we see some slow responses related to transfers taking some time.

[kaklakariada]

The "compression" flag will compress the messages after the login with zlib (see https://github.com/exasol/websocket-api/blob/master/docs/WebsocketAPIV3.md#compression). I assume this would improve performance for large queries or result sets. If this is the case I will add it to the roadmap.

[espenhogbakk]

Yes large queries would surely see a benfit of that. And it makes sense for the decompression to be handled by the driver instead of outside i think? And even if I wanted to try to do the decompression outside of the driver there is currently no supported way to configure the driver to use compression since the compression is not part of the Config interface we can pass into the initializer.