yt-dlp integration

NOTE:
**please use english, or include an english translation.** aside from that,
all of the below are optional, consider them as inspiration, delete and rewrite at will

**Describe the idea / solution you'd like**

I want to host videos and other media on copyparty for myself and wanted to add more videos to it. So instead of downloading videos and uploading them again, maybe a menu or adding to the uploader menu to paste links that get downloaded from the copyparty server to the current folder (maybe with advanced settings on youtube links to choose from preferred filetype and quality).
For copyparty to stay lightweight, yt-dlp may be installed seperatly.
For users who dont want to use this feature, maybe add it as a flag for folders/global to enable it.