Refactor | Added extension functions

[LinX64]

This PR is about polishing codes, and using extension functions for StateIn() (mostly in ViewModels).

Basically, all of the StateIn() functions inside ViewModels were following/using the same pattern, so I decided to create two extension functions for use in both ViewModels using viewModelScope, as well as CoroutineScope outside of ViewModels.

[SimonMarquis]

Suggested change

	viewModelScope: CoroutineScope,
	coroutineScope: CoroutineScope,

[manuelvicnt]

Unsure about adding this API / helper function to the Now in Android app.

It just saves you one line of code and the name (currently stateInScope) isn't clear what is doing or how it's different from the stateIn operator.

The ideal API for this would be a context receiver on both Flow and ViewModel so that you could have a Flow operator using the viewModelScope. e.g.

context(ViewModel)
fun Flow.produceState(
    coroutineScope: CoroutineScope = viewModelScope,
    started: SharingStarted = SharingStarted.WhileSubscribed(5_000),
    initialValue: T
): StateFlow<T> = ...

Until context receivers aren't widely available in Android and Compose, I'd refrain from adding a helper function for this functionality in a highly visible Android sample.

[LinX64]

Closing this PR as it is suggested to use Context receivers as a solution/replacement for the implementation.

P.S: This PR can wait for the Context Receivers to be available widely on Android and Kotlin.