Awaits a specified signal. [AwaitTweener] is used to await a specified signal, allowing asynchronous steps in [Tween] animation. See [method Tween.tween_await] for more usage information. The [signal Tweener.finished] signal is emitted when either the awaited signal is received, when timeout is reached, or when the target object is freed. Sets the maximum time an [AwaitTweener] can wait for the signal. Can be used as a safeguard for signals that may never be emitted. If not specified, the tweener will wait indefinitely.