RxJava3 Support

[michaelcarrano]

Roxie is built using RxJava2 and RxJava3 is in the works.

Things to think about:

• The operators that we currently use, are they still available? Do their behavior change?
  • If not available, what do we use instead?
  • If behavior change, does it break our implementation? What do we use instead?
• Should we provided an RxJava2 artifact? What Roxie is today.

https://github.com/ReactiveX/RxJava/releases/tag/v3.0.0-RC0

[nschwermann]

It doesn't look like there are any breaking changes to PublishSubject or CompositeDisposable so the library should only need a package change. I am thinking rather than having an Rx2 artifact it would be better to break Roxie into modules. The Base would be pretty much unchanged however there can be a different implementations for the ViewModel (rx2, rx3 and coroutine channel/flow)