Data Compression

### Problem Description

Now that this is launched, how about adding [the feature that eventually morphed into VPN to start with: compression!](https://github.com/AdguardTeam/AdguardForAndroid/issues/775)

Relevant quotes from that discussion:

@Eugene-Savenko:
> Please add data compression support. I know Google has an open source
> data compression protocol they both use in Chrome and Opera also has
> one. Maybe one of those can be implemented in the app to save data
> across all apps?
>
> **623633**

@war59312:
> Perhaps [Zstandard](https://code.facebook.com/posts/1658392934479273/smaller-and-faster-data-compression-with-zstandard/) could be used in some context.
>
> And/or [LS4](http://cyan4973.github.io/lz4/)

myself 😅:
> Maybe _optionally_ ask for protocol-level compression on **all** outbound requests, & go from there?
>
> [QUIC](https://en.m.wikipedia.org/wiki/QUIC)/[Brotli](https://en.m.wikipedia.org/wiki/Brotli) support?