Refactor app access (#205)

- Use `tt::app::` functions to start/stop apps and get current app(context) instead of using loader everywhere
- Removed `tt_service_loader.*` from TactilityC
- Created `tt_app_stop()` for TactilityC
- Bumped version to 0.3.0 to prepare for upcoming release

Tactility/Source/app/wifimanage/View.cpp

@@ -36,7 +36,7 @@ static void on_enable_switch_changed(lv_event_t* event) {
     if (code == LV_EVENT_VALUE_CHANGED) {
         bool is_on = lv_obj_has_state(enable_switch, LV_STATE_CHECKED);
 
-        auto wifi = optWifiManage();
+        auto wifi = std::static_pointer_cast<WifiManage>(getCurrentApp());
         auto bindings = wifi->getBindings();
 
         bindings.onWifiToggled(is_on);

Tactility/Source/app/wifimanage/WifiManage.cpp

@@ -14,16 +14,6 @@ namespace tt::app::wifimanage {
 
 extern const AppManifest manifest;
 
-/** Returns the app data if the app is active. Note that this could clash if the same app is started twice and a background thread is slow. */
-std::shared_ptr<WifiManage> _Nullable optWifiManage() {
-    auto appContext = service::loader::getCurrentAppContext();
-    if (appContext != nullptr && appContext->getManifest().id == manifest.id) {
-        return std::static_pointer_cast<WifiManage>(appContext->getApp());
-    } else {
-        return nullptr;
-    }
-}
-
 static void onConnect(const char* ssid) {
     service::wifi::settings::WifiApSettings settings;
     if (service::wifi::settings::load(ssid, &settings)) {