Fix single message mode not working when swipe between conversation feature is off

Due to some changes to introduce the 'swipe between convos' feature, the 'isSingleMessage' flag
is now being parsed from the nav stack using the wrong type, resulting in a fallback to 'false'
all the time.

Same goes for the viewModeIsConversation flag that's being passed to the new screen.

ET-5342

app/src/main/kotlin/ch/protonmail/android/navigation/route/HomeRoutes.kt

@@ -108,7 +108,7 @@ internal fun NavGraphBuilder.addConversationDetail(
                     // for the conversation view
                     isSingleMessageMode = singleMessageMode,
                     // for the message list grouping
-                    viewModeIsConversation = backStackEntry.arguments?.getBoolean(ViewModeIsConversation)!!,
+                    viewModeIsConversation = backStackEntry.arguments?.getString(ViewModeIsConversation)!!.toBoolean(),
                     entryPoint = ConversationDetailEntryPoint.valueOf(
                         backStackEntry.arguments?.getString(ConversationDetailEntryPointNameKey)!!
                     )
@@ -148,7 +148,7 @@ internal fun NavGraphBuilder.addConversationDetail(
                 ?.let(::MessageIdUiModel),
             openedFromLocation = LabelId(backStackEntry.arguments?.getString(OpenedFromLocationKey)!!),
             // for the conversation view
-            singleMessageMode = backStackEntry.arguments?.getBoolean(IsSingleMessageMode)!!,
+            singleMessageMode = backStackEntry.arguments?.getString(IsSingleMessageMode)!!.toBoolean(),
             conversationEntryPoint = ConversationDetailEntryPoint.valueOf(
                 backStackEntry.arguments?.getString(ConversationDetailEntryPointNameKey)!!
             ),