Adds a title and heading to new Files

fixes CNVS-15592

Test Plan:
  - Enable better files browsing
  - Go to files
  - An H1 tag should be there for screen readers only
  - The title in the header/tab should be present as well

Change-Id: I045b9516148b4adc5e351f17dd6d551c211631d1
Reviewed-on: https://gerrit.instructure.com/41945
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Ryan Shaw <ryan@instructure.com>
Product-Review: Ryan Shaw <ryan@instructure.com>
QA-Review: Jahnavi Yetukuri <jyetukuri@instructure.com>