Admin overview of the stores on the instance (#5745)

* Admin overview of the stores on the instance

POC/Draft for #5674.

* Enable admin to access foreign stores

* Remove stores list link

* UI updates

* Grant admins guest access to foreign stores

* Optimize cookie auth handler

* Test fix

* Revert changes related to StoreRepository.FindStore with isAdmin

BTCPayServer/Models/StoreViewModels/ListStoresViewModel.cs

@@ -1,4 +1,5 @@
 using System.Collections.Generic;
+using BTCPayServer.Data;
 
 namespace BTCPayServer.Models.StoreViewModels;
 
@@ -9,6 +10,7 @@ public class ListStoresViewModel
         public string StoreName { get; set; }
         public string StoreId { get; set; }
         public bool Archived { get; set; }
+        public List<UserStore> Users { get; set; }
     }
 
     public List<StoreViewModel> Stores { get; set; } = new ();