Admins can approve registered users (#5647)

* Users list: Cleanups

* Policies: Flip registration settings

* Policies: Add RequireUserApproval setting

* Add approval to user

* Require approval on login and for API key

* API handling

* AccountController cleanups

* Test fix

* Apply suggestions from code review

Co-authored-by: Nicolas Dorier <nicolas.dorier@gmail.com>

* Add missing imports

* Communicate login requirements to user on account creation

* Add login requirements to basic auth handler

* Cleanups and test fix

* Encapsulate approval logic in user service and log approval changes

* Send follow up "Account approved" email

Closes #5656.

* Add notification for admins

* Fix creating a user via the admin view

* Update list: Unify flags into status column, add approve action

* Adjust "Resend email" wording

* Incorporate feedback from code review

* Remove duplicate test server policy reset

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Co-authored-by: Nicolas Dorier <nicolas.dorier@gmail.com>

BTCPayServer/Models/ServerViewModels/UsersViewModel.cs

@@ -11,7 +11,8 @@ namespace BTCPayServer.Models.ServerViewModels
             public string Id { get; set; }
             public string Name { get; set; }
             public string Email { get; set; }
-            public bool Verified { get; set; }
+            public bool? EmailConfirmed { get; set; }
+            public bool? Approved { get; set; }
             public bool Disabled { get; set; }
             public bool IsAdmin { get; set; }
             public DateTimeOffset? Created { get; set; }