This fixes a bug in xblock serialization when trying to copy a
unit/component that contains an HTML xblock with the characters "]]>"
which is a special character in CDATA.
This fixes the issue when pasting a copied unit that contains
python_lib.zip file into another course. The python_lib.zip file was not
being correctly copied over to the new course's Files & Uploads page.
This takes into account the extra files that are usually required when
copying problems containing JSInputs. Static files such as additional
CSS and JS files needed to interact and style the problem.
* refactor: improve typing of StaticFile named tuple
* feat: copy static asset files into the clipboard
* feat: paste static assets
* feat: show notification in studio about pasted assets
* fix: HTML XBlocks would lose the editor="raw" setting when copy-pasted.
* feat: copy python_lib.zip to the clipboard when it seems to be in use
