Update Quickstart Sample to use beta.4

[mmacy]

@hamiltonha Heads-up that there are some changes here that you'll want to backfill into your quickstart and tutorial articles on docs.microsoft.com that this sample backs.

• https://docs.microsoft.com/azure/active-directory/develop/quickstart-v2-javascript-auth-code
• https://docs.microsoft.com/azure/active-directory/develop/tutorial-v2-javascript-auth-code

Cc: @sameerag @pkanher617