Use navigation argument topicId as default value to InterestListDetailScreen

Change-Id: I659f729191bce00683b1621c360c8f36f00595f9

app/src/main/kotlin/com/google/samples/apps/nowinandroid/ui/interests2pane/InterestsListDetailScreen.kt

@@ -33,6 +33,7 @@ import androidx.navigation.NavGraphBuilder
 import androidx.navigation.compose.NavHost
 import androidx.navigation.compose.composable
 import androidx.navigation.compose.rememberNavController
+import androidx.navigation.toRoute
 import com.google.samples.apps.nowinandroid.feature.interests.InterestsRoute
 import com.google.samples.apps.nowinandroid.feature.interests.navigation.InterestsDestination
 import com.google.samples.apps.nowinandroid.feature.topic.TopicDetailPlaceholder
@@ -45,20 +46,13 @@ import kotlinx.serialization.Serializable
 @Serializable object DetailPaneNavHostDestination
 
 fun NavGraphBuilder.interestsListDetailScreen() {
-    composable<InterestsDestination> {
-        InterestsListDetailScreen()
+    composable<InterestsDestination> { backStackEntry ->
+        val topicIdArgument = backStackEntry.toRoute<InterestsDestination>().topicId
+        var topicId: String? by rememberSaveable { mutableStateOf(topicIdArgument) }
+        InterestsListDetailScreen(selectedTopicId = topicId, onTopicClick = { topicId = it })
     }
 }
 
-@Composable
-internal fun InterestsListDetailScreen() {
-    var selectedTopicId: String? by rememberSaveable { mutableStateOf(null) }
-    InterestsListDetailScreen(
-        selectedTopicId = selectedTopicId,
-        onTopicClick = { topicId -> selectedTopicId = topicId },
-    )
-}
-
 @OptIn(ExperimentalMaterial3AdaptiveApi::class)
 @Composable
 internal fun InterestsListDetailScreen(