Generally glitchiness with duplicating components in a unit

[kdmccormick]

For background context: in this issue, I've outlined the glitchy behavior we're seeing when duplicating children of a container block:

• Glitchy editing experience when duplicating XBlock children #2499

While trying to determine the "expected" behavior for the above, I encountered a variety of weird behavior while trying to duplicate blocks just in the normal Unit editor, including:

• Popover editor not loading for problem editor:
  
• Popover editor did load when I tried it on another problem, but it scrolled to the wrong spot on the page
• Conditional block did not shows up as duplicated until I refreshed the page

I'm not sure whether there is 1 underlying issue or multiple, or how much of this is specific to my development environment, but I think we generally need some QA around duplication in some matrix of all the following scenarios:

• In a short unit
• In a long unit, where we'd expect the page to be scrolled to to the right place
• Within a short and a long container (once that bug is resolved)
• For a block with a pop-over editor (html/problem/video/itembank)
• For a block with a custom editor (drag-and-drop, ora, lti)
• For a block with children (split_test)