The feature has indeed been removed, as of the current version (I’m using 9.5), on the web and in the application.
Instead, you are supposed to either have your team all use the same Workspace, or “fork” the Collection or Environment to their personal Workspaces. There will soon be a way to do a Pull Request and have team members push their changes back to the original. But I don’t know how all the other team members would then pull the pushed changes back into their personal Workspaces, without forking again! There must be some new workflow they are cooking up that hasn’t been released yet. Until then, we are stuck with the partially-implemented and more complex fork functionality!!
I’ve contacted support and registered my frustration with the removal of a simple “share” function. they are reporting it to their product team. I included a link to this discussion.