Implemented missing file handling endpoints

Added contract update endpoint

PostFundManagement.Domain/Abstractions/IS3Service.cs

@@ -2,6 +2,8 @@ namespace PostFundManagement.Domain.Abstractions;
 
 public interface IS3Service
 {
-    ValueTask<Result<string>> UploadFileAsync(string fileName, Stream fileStream, string contentType, CancellationToken cancellationToken = default);
+    string GenerateCdnUrl(string fileKey);
+    ValueTask<Result<string>> GeneratePresignedUrlAsync(string fileKey, TimeSpan duration, string? contentType = null, CancellationToken cancellationToken = default);    
+    ValueTask<Result<string>> UploadFileAsync(string fileName, string subPath, Stream fileStream, string contentType, CancellationToken cancellationToken = default);
     ValueTask<Result> DeleteFileAsync(string fileKey, CancellationToken cancellationToken = default);
 }