initial work to split into dart_filament and flutter_filament

flutter_filament/example/windows/flutter/generated_plugin_registrant.cc

@@ -0,0 +1,17 @@
+//
+//  Generated file. Do not edit.
+//
+
+// clang-format off
+
+#include "generated_plugin_registrant.h"
+
+#include <flutter_filament/flutter_filament_plugin_c_api.h>
+#include <permission_handler_windows/permission_handler_windows_plugin.h>
+
+void RegisterPlugins(flutter::PluginRegistry* registry) {
+  FlutterFilamentPluginCApiRegisterWithRegistrar(
+      registry->GetRegistrarForPlugin("FlutterFilamentPluginCApi"));
+  PermissionHandlerWindowsPluginRegisterWithRegistrar(
+      registry->GetRegistrarForPlugin("PermissionHandlerWindowsPlugin"));
+}