Metadata for link previews of sweet posts

[toBeOfUse]

Right now, creating link previews to sweet posts only shows metadata for completely public posts, it would be possible to make link preview metadata work for all posts that the preview-creating user has permission to see just by forwarding their cookies along with the metadata request, or even to have each user's browser dynamically request the metadata for sweet link previews so that each user would get the link preview with metadata depending on whether they're currently allowed to see the linked post