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.
(NIT) would be great to update this naming convention in the header to represent the general module-label / module-metadata / module-metadata-item / module-item-label / module-item-value (with a clear module-library class added to the parent in case we'd like to style classes/libraries differently.