move flutter_filament plugin to federated structure

flutter_filament_federated/flutter_filament/example/regenerate_goldens.sh

@@ -0,0 +1,8 @@
+#!/bin/bash
+device=$1
+if [ -z "$device" ]; then
+    echo "Usage: $0 <device_id>"
+    exit 1;
+fi
+rm -f integration_test/goldens/{ios,macos,windows,android}/*.png
+flutter drive --driver=test_driver/integration_test_update_goldens.dart  -d $1 --target=integration_test/plugin_integration_test.dart