[PM-26099] Update public list members endpoint to include collections (#6503)

* Add CreateCollectionAsync method to OrganizationTestHelpers for collection creation with user and group associations

* Update public MembersController List endpoint to include associated collections in member response model

* Update MembersControllerTests to validate collection associations in List endpoint. Add JsonConstructor to AssociationWithPermissionsResponseModel

* Refactor MembersController by removing unused IUserService and IApplicationCacheService dependencies.

* Remove nullable disable directive from Public MembersController

test/Api.IntegrationTest/Helpers/OrganizationTestHelpers.cs

@@ -151,6 +151,28 @@ public static class OrganizationTestHelpers
         return group;
     }
 
+    /// <summary>
+    /// Creates a collection with optional user and group associations.
+    /// </summary>
+    public static async Task<Collection> CreateCollectionAsync(
+        ApiApplicationFactory factory,
+        Guid organizationId,
+        string name,
+        IEnumerable<CollectionAccessSelection>? users = null,
+        IEnumerable<CollectionAccessSelection>? groups = null)
+    {
+        var collectionRepository = factory.GetService<ICollectionRepository>();
+        var collection = new Collection
+        {
+            OrganizationId = organizationId,
+            Name = name,
+            Type = CollectionType.SharedCollection
+        };
+
+        await collectionRepository.CreateAsync(collection, groups, users);
+        return collection;
+    }
+
     /// <summary>
     /// Enables the Organization Data Ownership policy for the specified organization.
     /// </summary>