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/ServerViewModels/UsersViewModel.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using BTCPayServer.Data;
 using BTCPayServer.Services.Stores;
 
 namespace BTCPayServer.Models.ServerViewModels
@@ -17,6 +18,7 @@ namespace BTCPayServer.Models.ServerViewModels
             public bool IsAdmin { get; set; }
             public DateTimeOffset? Created { get; set; }
             public IEnumerable<string> Roles { get; set; }
+            public IEnumerable<UserStore> Stores { get; set; }
         }
         public List<UserViewModel> Users { get; set; } = new List<UserViewModel>();
         public override int CurrentPageCount => Users.Count;

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 ();