Epic 15: Editors are viewed in modals in Studio (parity with library component editing)

[jmakowski1123]

(this implements: openedx/platform-roadmap#385)

As a content author, I expect to have the same experience in working with my editors in Libraries as I do with my courses in Studio. In particular, I expect my editors to appear as models within the context of the content outline I am working in.

Current experience in Libraries that could carry over to Studio Courses with parity:

The modal should appear in context with everything else grayed out. The header remains the same.