* Revert r66878, completely misses the point of factoring out doEdit() in the first...

* Revert r66878, completely misses the point of factoring out doEdit() in the first place, which was to separate the UI layer from the backend layer, to support callers with alternate UIs or no UIs.
* Reverted followup 66880.
* Reverted dependent changes r67752, r68606, r68608, r68609. The point of deprecating insertArticle()/updateArticle() was to allow the UI code to be moved to EditPage. If you move that exact EditPage-specific functionality back into Article::doEdit(), and call it from all sorts of non-EditPage places, then we'll hit the same sorts of bugs we had before r14834.