Allow Admin to disable Two-Factor Authentication

[MikeAlhayek]

Fix #13954

Adding a feature to allow user that is able to edit users to also disable their 2FA.

In the process I fixed the following existing issues:

• Invalid Email confirmation link being send to the emails.
• When the Registration feature is disabled but the RegistrationSettings.UsersMustValidateEmail is set to true, the Users admin UI will show the "Send verification email" button next to the user.
• When the user clicks on "Send verification email" it did not work in the past because that action in in EmailConfirmation not Registration controller.

Also, I added "Actions" button next to the user and moved the following buttons into it

• Unlock
• Delete
• Send verification email
• Disable two-factor authentication << this was added.