initial focus is sub-optimal on the 'confirm' dialog for course content editor panel

[alicewriteswrongs]

Steps to Reproduce

Initial focus is on the 'X' in the corner, so to get to the 'Discard changes' button you need to press tab once.

Expected Behavior

I think when the 'You have unsaved changes. Are you sure you want to discard your changes?' dialog opens the initial focus should be on the 'Discard changes' button. That way you have two ways, via the keyboard, to go forward: press enter to discard changes, or press escape to cancel. Cancelling via the 'Cancel' button is also only one tab away.

I'm not sure exactly how we want to adjust this, but I was thinking about things in our editing flow that we might want to adjust to enable people to work more quickly and so on.

Screenshot or Screencast

this shows the (very minor!) issue with this:

Screen.Recording.2022-02-02.at.9.20.02.AM.mov