Make Course Card consistent between screen readers
Make Course Card consistent between screen readers

Fixes: CNVS-30977

Test Plan:
- Navigate to the Canvas dashboard

- Using NVDA, voice over, and jaws

- The color/image region on each dashboard card
  should now have a label identifying it

- If no image is present, it is read as 'course
  card color region for <course name>'

- If an image is present, it is read as 'course
  image for <course name>'

- The experience should be consistent for each
  supported screenreader

NOTE: When using jaws, it may call out 'blank'
when navigating the course card. This is normal
behavior for jaws as it is used to identify
content separation.

Change-Id: I89569c1c8c0a5e3aa1d52e0e141a6c1b95f1e91c
Reviewed-on: https://gerrit.instructure.com/88859
Tested-by: Jenkins
Reviewed-by: Pam Hiett <7b533437add1ce4ea4ed79979fa88e0e484e554b@instructure.com>
QA-Review: Pierce Arner <de38b793164d9bfa12fc4185260c174139808169@instructure.com>
Product-Review: Pam Hiett <7b533437add1ce4ea4ed79979fa88e0e484e554b@instructure.com>

djbender/canvas-lms,venturehive/canvas-lms,dgynn/canvas-lms,instructure/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,dgynn/canvas-lms,dgynn/canvas-lms,instructure/canvas-lms,SwinburneOnline/canvas-lms,grahamb/canvas-lms,HotChalk/canvas-lms,grahamb/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,matematikk-mooc/canvas-lms,grahamb/canvas-lms,djbender/canvas-lms,SwinburneOnline/canvas-lms,matematikk-mooc/canvas-lms,matematikk-mooc/canvas-lms,sfu/canvas-lms,djbender/canvas-lms,grahamb/canvas-lms,HotChalk/canvas-lms,instructure/canvas-lms,grahamb/canvas-lms,matematikk-mooc/canvas-lms,instructure/canvas-lms,HotChalk/canvas-lms,HotChalk/canvas-lms,venturehive/canvas-lms,instructure/canvas-lms,SwinburneOnline/canvas-lms,dgynn/canvas-lms,instructure/canvas-lms,venturehive/canvas-lms,SwinburneOnline/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,venturehive/canvas-lms,sfu/canvas-lms,sfu/canvas-lms