feat: add service manager

[vgonkivs]

Some time ago we discussed with @Wondertan that at some point we'll need some kind of service that can manage our services.
The first use case, that it could handle is simplifying our ServiceBreaker. TLDR: ServiceBreaker wraps some of our services and stops them once BEFP appeared. But it has one disadvantage - each service has to create its pubsub subscription over the BEFP topic. But we can have a service that creates a single subscription, waits for the BEFP, and then stops all respective services. This is only one use case that I can imagine rn, but I'm sure we can find more in the future.

type Service interface {
    Attach(topic string, stop func(context.Context) error) error
    Detach(topic string) error
}

[renaynay]

i'm fine with this approach, let's make it internal. Not high prio but would help clean up nodebuilder for sure. Thoughts on making this a good first issue ?

[vgonkivs]

I don't mind making it a good first issue. Should I prepare a detailed step-by-step explanation of what should be done? cc @Wondertan

[vgonkivs]

But I'd also propose to make an EPIC for this because the task can be decoupled

[Wondertan]

I don't think this is something a newcomer can handle. I would visit the manager once we have time to do refactorings on the nodebuilder.

[Wondertan]

Is this targeted particularly for managing PubSub subscriptions?

[vgonkivs]

At this point, yes. But I'm opened to any suggestions. We can make it configurable to manage whatever