Onboarding: Invite new users (#5714)

* Server Users: More precise message when inviting users

This lets the admin who invited a new user know whether or not an email has been sent. If the SMTP server hasn't been set up, they need to share the invite link with the user.

* Onboarding: Invite new users

- Separates the user self-registration and invite cases
- Adds invitation email for users created by the admin
- Adds invitation tokens to verify user was invited
- Adds handler action for invite links
- Refactors `UserEventHostedService`

* Remove duplicate status message from views that use the wizard layout

* Auto-approve users created by an admin

* Notify admins via email if a new account requires approval

* Update wording

* Fix update user error

* Fix redirect to email confirmation in invite action

* Fix precondition checks after signup

* Improve admin notification

Send notification only if the user does not require email confirmation or when they confirmed their email address. Rationale: We want to inform admins only about qualified users and not annoy them with bot registrations.

* Allow approval alongside resending confirm email

* Use user email in log messages instead of ID

* Prevent unnecessary notification after email confirmation

* Use ApplicationUser type explicitly

* Fix after rebase

* Refactoring: Do not subclass UserRegisteredEvent

BTCPayServer/Controllers/UIServerController.cs

@@ -16,9 +16,7 @@ using BTCPayServer.Abstractions.Models;
 using BTCPayServer.Configuration;
 using BTCPayServer.Data;
 using BTCPayServer.HostedServices;
-using BTCPayServer.Hosting;
 using BTCPayServer.Logging;
-using BTCPayServer.Models;
 using BTCPayServer.Models.ServerViewModels;
 using BTCPayServer.Models.StoreViewModels;
 using BTCPayServer.Payments;
@@ -26,10 +24,8 @@ using BTCPayServer.Services;
 using BTCPayServer.Services.Apps;
 using BTCPayServer.Services.Mails;
 using BTCPayServer.Services.Stores;
-using BTCPayServer.Storage.Models;
 using BTCPayServer.Storage.Services;
 using BTCPayServer.Storage.Services.Providers;
-using BTCPayServer.Validation;
 using Microsoft.AspNetCore.Authorization;
 using Microsoft.AspNetCore.Cors;
 using Microsoft.AspNetCore.Identity;
@@ -1180,7 +1176,7 @@ namespace BTCPayServer.Controllers
             return View(vm);
         }
 
-        [Route("server/emails")]
+        [HttpGet("server/emails")]
         public async Task<IActionResult> Emails()
         {
             var email = await _SettingsRepository.GetSettingAsync<EmailSettings>() ?? new EmailSettings();
@@ -1191,8 +1187,7 @@ namespace BTCPayServer.Controllers
             return View(vm);
         }
 
-        [Route("server/emails")]
-        [HttpPost]
+        [HttpPost("server/emails")]
         public async Task<IActionResult> Emails(ServerEmailsViewModel model, string command)
         {
             if (command == "Test")
@@ -1246,7 +1241,7 @@ namespace BTCPayServer.Controllers
                 return View(model);
             }
             var oldSettings = await _SettingsRepository.GetSettingAsync<EmailSettings>() ?? new EmailSettings();
-            if (new EmailsViewModel(oldSettings).PasswordSet)
+            if (new ServerEmailsViewModel(oldSettings).PasswordSet)
             {
                 model.Settings.Password = oldSettings.Password;
             }