Studio support for creating and editing libraries (PR 6046)

Duplicates https://github.com/edx/edx-platform/pull/6046 to allow Marco to review without spamming the reviewers on the original PR.
We don't use id based selectors, and are also removing all pure element selectors with an upcoming sass cleanup, so it would be good to replace this and any other id/element based selectors from this diff.