User: Add name and image URL (#6008)

* User: Add name and image URL

More personalization options, prerequisite for btcpayserver/app#3.

Additionally:
- Remove ambigious and read-only username from manage view.
- Improve email verification conditions and display.
- Greenfield: Update current user. Prerequisite for btcpayserver/app#13.

* Refactor UpdateCurrentUser

* Replace new columns by UserBlob

* Update email check and add test case for mailbox addresses

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

BTCPayServer/Models/StoreViewModels/StoreUsersViewModel.cs

@@ -9,6 +9,8 @@ namespace BTCPayServer.Models.StoreViewModels
         {
             public string Email { get; set; }
             public string Role { get; set; }
+            public string Name { get; set; }
+            public string ImageUrl { get; set; }
             public string Id { get; set; }
         }
         [Required]