androidx-2.1.0
This is a new release for androidX. From 2.1.0 (Kotlin 1.3.0), we don't support the AppCompat library.
Release
1. Upgrade Kotlin version to 1.3.0
2. Upgrade Kotlin Coroutines version to 1.0.0
3. Fix the Coroutines API for fitting the new Coroutines API
4. Add 2 extensions API for `IO` & `background` → `io { }` & 'bkg { }'