[Content editor][Back port]Add "Edit as draft" menu option

Add "Edit as draft" menu option

As a user
when I open a document in preview mode
and the document has been "saved as draft"
then the option "edit as draft" is available
so I enable collaboration with another user.

As as user
when I open a document in preview mode
and I "edit as draft" for that document
then I have the open to "save" and "save as draft"
and I am able to edit the draft
so I can collaborate with the previous user that edited the document