Use C++20 coroutines in AUI

[Alex2772]

Coroutines is modern and efficient way to create multithreaded UI apps.

[Alex2772]

As now, it seems only Windows and Linux support coroutines.

Also, I tested the new coroutines feature on production code, which leads the compiler to crash:

/home/alex2772/CLionProjects/golden-egg/watcher/src/binance/scalping.cpp: In function ‘AFuture<AVector<LeaderboardEntry> > scalping::getLeaderboard()’:
/home/alex2772/CLionProjects/golden-egg/watcher/src/binance/scalping.cpp:90:1: internal compiler error: in build_special_member_call, at cp/call.cc:11093
   90 | }
      | ^
Please submit a full bug report, with preprocessed source.
See <http://bugzilla.redhat.com/bugzilla> for instructions.
Preprocessed source stored into /tmp/ccMaZAge.out file, please attach this to your bugreport.

As for now, I will disable the feature by default and merge the PR. I will not close the feature request though, as implementation remains untested.