[iOS][Bookmarks] Editor deals with deleted ancestor.

If the node is deleted, the editor is closed.

If the bookmark or folder was going to be moved to a deleted folder
(including by signing-out), the node is moved to Mobile Bookmarks, if
possible of the same model.

This ensure:
* that both kind of editors behaves in a similar way
* that "done" is never ignored (which used to be the case when a node
  was moved to a deleted folder
* that if the node is actually deleted, it’s reflected in the view.

Fixed: 330345514
Change-Id: Ia6da53f21821dc73cbc2d412ad1f77d945c8e1ef
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5382411


Reviewed-by: Tanmoy Mollik <triploblastic@google.com>
Commit-Queue: Arthur Milchior <arthurmilchior@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1278430}