Showkase navigation breaks when preview contains a BackHandler

[vinaygaba]

Fixes #247

Description of the issue

If you have BackHandler which does nothing inside @Preview it breaks navigation for Showkase browser

Snippet to reproduce:

@Composable
fun ContentScreen(
    viewModel: ContentViewModel = androidx.lifecycle.viewmodel.compose.viewModel(),
) {
    Content(onBack = viewModel::onBack)
}

@Composable
fun Content(onBack: () -> Unit) {
    BackHandler(onBack = onBack)
}

@Preview
@Composable
fun ContentPreview() {
    Content(
        onBack = {},
    )
}

If you open ContentPreview from Showkase browser, it will not be possible to navigate back

@airbnb/showkase-maintainers