[Feature] add toggle for 'external library watch' watch folder only instead of every single file/photo in the external library

I have searched the existing feature requests, both open and closed, to make sure this is not a duplicate request. • Yes The feature once turning the external library watch, immich showing logs as below * (total files in the external library - 8192), and eventually the library watch function not working anymore. understand the current idea of the watch function is to include the photo editing etc. But normally a photo library would have more than 8k photos, but most likely no more than 8k folders for personal/home use. so I would request to add a toggle of whether to scan the folders/subfolders only instead of every single file. this way the new photo addition/deletion could be monitored but the photo edition would be reflected by periodical scan. even though extending the fs.inotify.max_user_watches to more than photo number in the library could solve the problem temporarily, but with the library size increasing, the solution is not practical any more when it reaches c…