Remove the legacy registerWith(PluginRegistry.Registrar) implementation and PluginRegistry import from AMapFlutterMapPlugin to rely on the newer Flutter embedding lifecycle. In ConvertUtil, replace deprecated FlutterMain.getLookupKeyForAsset calls with FlutterInjector.instance().flutterLoader().getLookupKeyForAsset and update imports accordingly (affects both fromAsset and fromAssetImage paths). These changes migrate the plugin to the newer Flutter loader/embedding APIs.