implement FileUploadService and chunked upload models

Services/FileUploadMethods.cs

@@ -0,0 +1,34 @@
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using Chtn.CSharp.SDK.Core;
+using Chtn.CSharp.SDK.Models.Media;
+
+namespace Chtn.CSharp.SDK.Services
+{
+    public interface IFileUploadService
+    {
+        Task<RegisterUploadResp> UploadFiles(RegisterUploadReq req);
+        Task<RegisterUploadResp> UploadFile(RegisterUploadReq req);
+        Task UploadChunk(ChunkUploadReq req);
+    }
+
+    public class FileUploadServiceProvider : IFileUploadService
+    {
+        private readonly ApiClient _apiClient;
+        
+        public FileUploadServiceProvider(ApiClient apiClient)
+        {
+            _apiClient = apiClient ?? throw new ArgumentNullException(nameof(apiClient));
+        }
+
+        public async Task<RegisterUploadResp> UploadFiles(RegisterUploadReq req) =>
+            await _apiClient.PostAsync<RegisterUploadReq, RegisterUploadResp>("chat/cdnRegisterUpload", req);
+
+        public async Task<RegisterUploadResp> UploadFile(RegisterUploadReq req) =>
+            await UploadFiles(req);
+
+        public async Task UploadChunk(ChunkUploadReq req) =>
+            await _apiClient.PostAsync<ChunkUploadReq, object>("chat/uploadChunk", req);
+    }
+}