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.
If this is the same library code that users choose for their libraries at creation time, then the label should match that field (Library Code). If it is the identifier that the system creates in the URL, then perhaps "Library Identifier" (I'm not sure if it is a number). @frrances @marcotuts what are your thoughts?