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Memory leak using "LifecycleExt.kt"

See original GitHub issue

Hello Arkadiy, thank you very much for such a great library!

It seems to me there is a memory leak in this file: https://github.com/arkivanov/MVIKotlin/blob/bad123550ff7e451708280efbc4394ffdc347107/mvikotlin/src/commonMain/kotlin/com/arkivanov/mvikotlin/core/lifecycle/LifecycleExt.kt#L49

Probably for all these methods: Lifecycle.doOnResumePause, Lifecycle.doOnPause, Lifecycle.doOnStartStop, Lifecycle.doOnStop.

As soon as an anonymous callback instance is created, there is no chance to remove this object until onDestroy event. And if someone uses these methods in onStart then on each call a new callback will be added to LifecycleRegistry.

As a variant to fix that, I can suggest returning Disposable to let a client to remove/unsubscribe from LifecycleRegistry in this way:

inline fun Lifecycle.doOnResumePause(crossinline onResume: () -> Unit, crossinline onPause: () -> Unit): Disposable {
    val callbacks = object : DefaultLifecycleCallbacks {
        override fun onResume() {
            onResume.invoke()
        }

        override fun onPause() {
            onPause.invoke()
        }
    }
    subscribe(callbacks)
    return CancellableDisposable { unsubscribe(callbacks) }
}

// Then from the client side we can call `disposable?.dispose()` to remove added callback.

At the same time there is no such issue with Lifecycle.doOnDestroy and Lifecycle.doOnCreateDestroy (at least on Android platform) because Android LifecycleRegistry removes a callback automatically after onDestroy event.

@arkivanov does it make sense?