Implement admin endpoints

OpenSaveCloudClient/Models/Remote/Registration.cs

@@ -0,0 +1,17 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Text.Json.Serialization;
+using System.Threading.Tasks;
+
+namespace OpenSaveCloudClient.Models.Remote
+{
+    public class Registration
+    {
+        [JsonPropertyName("username")]
+        public string Username { get; set; }
+        [JsonPropertyName("password")]
+        public string Password { get; set; }
+    }
+}