3.x: Revise AtomicThrowable.addThrowable usage

[akarnokd]

Currently, many (if not all?) usage of addThrowable is as follows:

if (errors.addThrowable(ex)) {
   // do something with the error case
} else {
    RxJavaPlugins.onError(ex);
}

The plugin error call could be inlined into the method call and renamed to tryAddThrowable to ensure all usage places are updated correctly.

[RomanWuattier]

Hey, do you need help doing this?

[akarnokd]

Each usage location has to be reevaluated and there are thousands of those. It would be easier if I do them.