Put focus on the password recovery flash (a11y)
Put focus on the password recovery flash (a11y)

Refs USERS-450
Refs UXS-50

Accessibility audit pointed out that after the password reset
instructions are issued, focus should be on the alert that just
got put up, not back on the email input field.

Test plan:
* At the Canvas login page, click on "Forgot Password?"
* Enter an email address and click on "Request Password"
* Flash message should come up about the reset message being
  sent
* Focus should be on the close X button of that flash message

Change-Id: I1dd5eb5e94378e1ffd782f2ce16694baed677783
(cherry picked from commit 94037b42fb0566e188423bacc0635b01637407b3)
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/231338
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>
Reviewed-by: Keith Garner <a1a80143a840c140f31c3495ebbd9ec906e09fed@instructure.com>
QA-Review: Daniel Sasaki <ae19fabf7fe19dff310008c9b6a4d2ec84d311d8@instructure.com>
Product-Review: KC Naegle <9fbecd016338f9910821a8a5d5d0ae4fc9abfaa5@instructure.com>

sfu/canvas-lms,sfu/canvas-lms,djbender/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,djbender/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,sfu/canvas-lms