Implement public page listing public collections

[tw4l]

Context

Now that we have public collections, users may want to direct people to a listing of the public collections that are available to view. This could include the name, description, and a link to each, and would help discoverability of the collections that have been made public, which are otherwise only discoverable if you already have the URL.

Requirements

• List page (publicly accessible with a link) of collections with thumbnail images that an org has made public, clicking on each thumbnail directs users into a full page ReplayWebpage viewer for that collection where they can then view highlighted pages