rework messages

+ addition LocalStorageService
+ tests

Govor.API/Services/IStorageService.cs

@@ -0,0 +1,10 @@
+using Microsoft.AspNetCore.Http; // для IFormFile
+
+namespace Govor.API.Services;
+
+public interface IStorageService
+{
+    Task<string> SaveAsync(byte[] data, string fileName);
+    Task<Stream> LoadAsync(string url);
+    Task RemoveAsync(string url);
+}