Makes module titles more accessible

Modules collapsed/expanded state is now indicated by screenreaders
The module title can now be accessed and expanded/collapsed
by keyboard only users. It is essentially a temporary fix for
a couple of issues until the module page can be refactored.

closes CNVS-14721

test plan:
  - Using a screenreader (specifically JAWS is requested)
  - Go to the modules page (/courses/##/modules)
  - The module titles should not be recognized as headers
  - Navigate to a module title header.
  - The module should be able to be expanded/collapsed using the
    keyboard
  - The screenreader should announce if the module is expanded or
    collapsed.

Change-Id: I40277af739d8be1f1bb5b19aee205dfbee7c615f
Reviewed-on: https://gerrit.instructure.com/40826
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Clare Strong <clare@instructure.com>
Reviewed-by: Jeremy Stanley <jeremy@instructure.com>
Product-Review: Cosme Salazar <cosme@instructure.com>