Admin panel for adding/remove user email address for password authentication.

[lyndaidaii]

Summary of the changes (in less than 80 characters):

• Show list of exception list for password authentication
• Remove/Add email from exception list
• View the user credential if is IsAADorMACredential

rec-screen.1.webm

Addresses https://github.com/NuGet/Engineering/issues/4731

[keylime-unicorn]

I noticed some of the added files are missing the copyright header comment.

[lyndaidaii]

Next steps:
we will have separate PRs for following:

1. Add Aduit
2. We have another admin panel for allowlist, during that work, we are going to refactor the code since feature flags, email, allowlist are all read, write from storage container. we will build more general base function so that 3 services could use and reduce duplicate code.

[lyndaidaii]

@joelverhagen , @zhhyu , @TheoT12 could you help review again since I applied some changes. Thanks!

[lyndaidaii]

@agr , @TheoT12 addressed your comments, please let me know if you have any questions/comments.