Pre and post fling

pre-post-fling.kt

override suspend fun onPreFling(available: Velocity): Velocity {
    return if (available.y < 0 && scrollState.value == 0) {
        swipeableState.performFling(available.y)
        available
    } else {
        Velocity.Zero
    }
}

override suspend fun onPostFling(
    consumed: Velocity,
    available: Velocity
): Velocity {
    swipeableState.performFling(velocity = available.y)
    return super.onPostFling(consumed, available)
}