Add REffectBuilder

[turansky]

Fix #463. Part 1

[turansky]

@sgrishchenko Draft for part 2:

fun useEffectOnce(
    effect: REffectBuilder.() -> Unit,
) {
    val callback = useEffectCallback(effect)
    rawUseEffect(callback, emptyArray())
}

fun useEffect(
    vararg dependencies: dynamic,
    effect: REffectBuilder.() -> Unit,
) {
    val callback = useEffectCallback(effect)
    rawUseEffect(callback, dependencies)
}

[Leonya]

Released in pre.208