implement drag-n-drop move for newfiles

closes: CNVS-14866

also, fixes some specs that were really brittle and
causing lots of pain and frustration with jenkins.

test plan:
open newfiles
select some things
try dragging them to another folder on the page
it should work equally as well to drop on folders
shown in the left folder tree as well as
folders shown in the main panel

Change-Id: Ieaca31640146dbf570a8525733199eb1b8f00c14
Reviewed-on: https://gerrit.instructure.com/41957
Reviewed-by: Clay Diffrient <cdiffrient@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: Ryan Shaw <ryan@instructure.com>
QA-Review: Ryan Shaw <ryan@instructure.com>