Allow option for collaborators to share the album link

[ymilly]

When making an album shareable, have an option "allow collaborators to share the link with others"

Use case: when I add as a collaborator, I still have to provide them with the link to each album.

I understand this might be the desired use in some cases: I want you to collaborate, but I don't want you to be able to share this with others.

Making this a toggle option (default off), would allow for retaining the current usage, while still making it possible for collaborators to get the shareable link, if desired, by the album creator.