Implement AuthService and ApiClient core logic

Models/CommonModels.cs

@@ -0,0 +1,32 @@
+using Newtonsoft.Json;
+
+namespace Chtn.CSharp.SDK.Models.Common
+{
+    public class RGB
+    {
+        public int R { get; set; }
+        public int G { get; set; }
+        public int B { get; set; }
+    }
+
+    public class TimeStamp
+    {
+        [JsonProperty("T")] public long T { get; set; }
+        [JsonProperty("I")] public int I { get; set; }
+    }
+    public class PublicUserData
+    {
+        [JsonProperty("pfp")] public string Pfp { get; set; }
+        [JsonProperty("displayName")] public string DisplayName { get; set; }
+        [JsonProperty("username")] public string Username { get; set; }
+        [JsonProperty("userid")] public string UserId { get; set; }
+    }
+
+    public class Attachment
+    {
+        public string FileId { get; set; }
+        public string FileName { get; set; }
+        public string Path { get; set; }
+        public string Type { get; set; }
+    }
+}