Feature: viewmodel-lifecycle-rxkotlin2/rxkotlin3 modules

[skydoves]

Overview

Introduce a new extension autoDisposable.. autoDisposable creates a [Disposable] read-only delegate property, which will call the Disposable.dispose() when the ViewModel is cleared.

class SecondViewModel : ViewModel() {

  // The compositeDisposable will be called `dispose` automatically when the VeiwModel is cleared.
  val compositeDisposable by autoDisposable(CompositeDisposable())

#2