Refactored manifest onStart/onStop to onCreate/onDestroy (#195)

When writing documentation, I realized how `onStart`/`onStop` isn't clearly communicating what it does (it could imply show/hide), so I renamed it to `onCreate` and `onDestroy`.

Tactility/Source/app/timezone/TimeZone.cpp

@@ -231,7 +231,7 @@ public:
         listWidget = list;
     }
 
-    void onStart(AppContext& app) override {
+    void onCreate(AppContext& app) override {
         updateTimer = std::make_unique<Timer>(Timer::Type::Once, updateTimerCallback, nullptr);
     }
 };