Don't proxy S3 links

Don't proxy S3 links: Is your feature request related to a problem? Please describe. There is a use case for allowing files to be downloaded directly from S3 instead of being proxied by the instance that is running NextCloud. The first and biggest pro for this is cost reduction. The transfer from S3 to the internet is much much lower than from EC2 to the internet. The second pro is speed. S3 will serve the file as fast as possible, while your EC2 instance will server the file at a speed that could vary because of the CPU usage, network...