Fix infinite recomposition when state properties used in composition

[kemalatli]

Infinite recomposition occurs when state properties such as draggingItemTop and draggingItemLeft are called within composition. Usecase would be to subscribe on these values via LaunchedEffect to customize certain UI behavior like below.

val state = rememberReorderableLazyListState(onMove = vm::moveDog, canDragOver = vm::isDogDragEnabled)
LaunchedEffect(
        key1 = state.draggingItemKey,
        key2 = state.draggingItemTop,
        block = {
            Log.d("TAG", "NewVerticalReorderList: ${state.draggingItemTop}")
            if(state.draggingItemTop>50f){
                **// Do call custom logic in here... **
            }
        }
)
LazyColumn(
        state = state.listState,
        modifier = modifier
            .then(Modifier
                .reorderable(state)
                .detectReorderAfterLongPress(state))
)

Steps to reproduce this bug is to add the above LaunchedEffect in the sample project. This PR addresses the issue by simply checking the draggingItemKey existence. So that this value can only be fetched from draggingLayoutInfo only if there is an acitve dragged item.

Here is how hwui rendering looks like under infinite recomposition.

infinite-recomposition.mov

[bpappin]

I have cloned this PR into my own fork:
bpappin#1