updating submission workflow to resolve RDR-649:
- removes cost calculator step from submission form, retains view code as a partial (_cost_calculator.html.erb)
- adds 'over 300GB' to screened out logic, sends email after selecting 300gb and submitting
- adds progress indicator to bottom of form to improve a11y
- disables window-history (back button) while in form
- removes PACE workflow question, retains vew code as a partial (_pace.html.erb)