Avoid calling Window.setVisible(true) on every AwtWindow recomposition

[m-sasha]

Currently, we're calling Window.isVisible = true on every AwtWindow recomposition, which has the unfortunate side-effect of calling Window.toFront().

Proposed Changes

Replace the SideEffect + DisposableEffect that shows/hides the window with just one

   DisposableEffect(currentVisible) {
        val showJob = GlobalScope.launch(MainUIDispatcher) {
            window().isVisible = currentVisible
        }

        onDispose {
            showJob.cancel()
        }
    }

Testing

Test: Added two unit tests: one to test that a window isn't brought to front when recomposed, and another (per @igordmn's request) that rendering in the parent window isn't blocked by a modal DialogWindow.

Issues Fixed

Fixes: JetBrains/compose-multiplatform#2994