Add Flow.onErrorComplete operator

[pjfanning]

Discussed in #623

^{Originally posted by He-Pin September 2, 2023}
When we encounter an exception, sometime we may don't want the flow to result in an error but completes normally.

The implementation can be simple, but still cause some confusing.

I would like suggest to add a onErrorComplete operator which will complete the flow on some dedicated condition.

And better we have another onErrorContiune operator, which will keep the flow working but will need the operator before it to support this.

[nvollmar]

Maybe we could lean the design on the akka.actor.SupervisorStrategy having a decider that returns Fail, Complete or Continue

[He-Pin]

@nvollmar That's a good idea.

[He-Pin]

@nvollmar I'm planning to handle this this weekend, onething I have in mind is we can have something like the reactor-core's operator name, which is very easy to use and accessiable. so I would like to continue with onErrorComplete name, and I mostly using Javadsl.

Your proposal is generic and great .

[nvollmar]

I'm back home, so I'd be available for a review, just request me on the PR

[He-Pin]

In spring-projects/spring-framework#31352 which split the usage of onErrorResume