Fix folder crash where view is added when it already has a parent.

The fix is to prevent re-arrangement if the views are already unbound.

This is caused when:
- Folder is open
- Item has deep shortcuts
- Long press on deep shortcut to create DragView that could land in the
  folder if the folder did not auto close. This is important because it
  starts a drag within the folder

The folder unbinds all views as part of the Folder close complete callback.
And then the folder exit alarm gets triggered (because we drag DragView
outside of the folder) which causes the folder items to get
rearranged and added back to the folder's CellLayout.

Bug: 161559911
Change-Id: I142589b2c541dc21c47a67c20a93e627732107ef