capitalize the first letter of extra attempt button
capitalize the first letter of extra attempt button

closes gh-1961
closes EVAL-2133
flag=none

Test Plan:
- Submit a quiz or anything which allows viewing of the page with the
  button
- View page which shows the button
- Ensure that the text on the button is "Allow this student an extra
  attempt"

Change-Id: I21f7c11881ac8a65003b027a4f8b2512b22a9bbd
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/280368
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>
Reviewed-by: Aaron Shafovaloff <d0ee6b99167c663aba7bc3efd806fe8d6cad437b@instructure.com>
QA-Review: Aaron Shafovaloff <d0ee6b99167c663aba7bc3efd806fe8d6cad437b@instructure.com>
Product-Review: Jody Sailor

instructure/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,sfu/canvas-lms