Handle topic clicks from all destinations

Closes #865

app/src/main/java/com/google/samples/apps/nowinandroid/navigation/NiaNavHost.kt

@@ -49,8 +49,7 @@ fun NiaNavHost(
         startDestination = startDestination,
         modifier = modifier,
     ) {
-        // TODO: handle topic clicks from each top level destination
-        forYouScreen(onTopicClick = {})
+        forYouScreen(onTopicClick = navController::navigateToTopic)
         bookmarksScreen(
             onTopicClick = navController::navigateToTopic,
             onShowSnackbar = onShowSnackbar,
@@ -61,13 +60,11 @@ fun NiaNavHost(
             onTopicClick = navController::navigateToTopic,
         )
         interestsGraph(
-            onTopicClick = { topicId ->
-                navController.navigateToTopic(topicId)
-            },
+            onTopicClick = navController::navigateToTopic,
             nestedGraphs = {
                 topicScreen(
                     onBackClick = navController::popBackStack,
-                    onTopicClick = {},
+                    onTopicClick = navController::navigateToTopic,
                 )
             },
         )