Download media also from Shared albums

Summary

Add ability to download photos and videos from Shared Albums

Context

Shared albums are used frequently between family members, as a repository for photos where everyone can contribute.

Right now, with icloudpd, you can download all the photos/videos that you took, but photos other put in a shared album can not be downloaded.

I would be great to be able to download a copy of these photos like any other album.