Switched to a new Actor implementation

[ogaclejapan]

Improve actor disposing to avoid ClosedSendChannelException.

The issue arises when the code is executed in a specific sequence, leading to a reference to an already closed query.

1. caller:  client.getQuery(key)
2. swr-cache: query.close()
3. caller: query.start() // <-- ClosedSendChannelException !!!

In the current implementation of the Actor, the Actor is only started when onLaunchedEffect is executed. As a result, there is a delay between retrieving the query and starting the Actor, which exposed a design flaw.

To address this issue, we needed to carefully examine the implementation of the Actor and ensure that it aligns with the following well-defined requirements:

1. Accurately return the appropriate query (whether new or reused) when called upon.
2. Independently carry out the disposal process of the Actor, without being influenced by the order of execution between concurrent operations.

In the new design, query.start is decoupled from launchIn(scope), effectively synchronizing the Actor state at the timing of the getQuery call. This mechanism allows for the detection of state differences even within delayed disposal processes on the main thread, ensuring safe closure.