Create delegate rules API, extract AutoDispose handling to separate artifact

[ZacSweers]

Right now we've hardcoded AutoDispose support directly in. We should make an API that allows for provisioning of separate handlers to extract observers.

Let's start with something simple: accept a list of handlers, first one to consume it wins, otherwise built-in implementation takes over.

We can look later at doing something more Retrofit-style with delegating/forwarding if need be.

[ZacSweers]

Simple interface:

interface DogTagChecker {
  default boolean shouldDecorateWithDogTag(Observable<?> observable, Observer<?> observer) {
    return false;
  }
  
  // Add overloads for all the other types
}

And make the default handling the last entry in the list.