feat(attachments)!: cater for subdirectories in storage

[DominicGBauer]

Description

• Allow subdirectories in storage to also be used in attachments queue
• Rename methods to make them more general

Work Done

• Allow subdirectories to be set on queue initializing which will create a subdirectory locally to match what is on remote storage
• Renamed savePhoto and deletePhoto methods to saveFile and deleteFile - this introduces a BREAKING CHANGE

How to test

Using todolist demo:

1. When initializing the queue in queue.dart add a subdirectory e.g. ['cover-images']

  PhotoAttachmentQueue(db, remoteStorage)
      : super(
            db: db,
            remoteStorage: remoteStorage,
            onDownloadError: onDownloadError,
            subdirectories: ['cover-images']);

2. Update _takePhoto method in photo_capture_widget.dart to this (bold is what has been changed, the ID now captures the subdirectory):

  Future<void> _takePhoto(context) async {
    try {
      // Ensure the camera is initialized before taking a photo
      await _initializeControllerFuture;

      final XFile photo = await _cameraController.takePicture();
      // copy photo to new directory with ID as name
      String subdirectory = 'cover-images'; <--------
      String photoId = '$subdirectory/${powersync.uuid.v4()}'; <--------
      String storageDirectory = await attachmentQueue.getStorageDirectory();
      await attachmentQueue.localStorage
          .copyFile(photo.path, '$storageDirectory/$photoId.jpg');

      int photoSize = await photo.length();

      TodoItem.addPhoto(photoId, widget.todoId);
      attachmentQueue.saveFile(photoId, photoSize);
    } catch (e) {
      log.info('Error taking photo: $e');
    }

    // After taking the photo, navigate back to the previous screen
    Navigator.pop(context);
  }

3. Load the app and take a photo after creating a todo
4. You should see the image in a subfolder on supabase
5. Load the app on another device and you should see the image download onto the device and display correctly