added UserContext for easy UserId getting

started writing custom services to implement users logic

SurveyBackend/SurveyBackend.API/Contexts/UserContext.cs

@@ -0,0 +1,19 @@
+using System.Security.Claims;
+using SurveyBackend.Core.Contexts;
+
+namespace SurveyBackend.Contexts;
+
+public class UserContext : IUserContext
+{
+    private readonly IHttpContextAccessor _httpContextAccessor;
+
+    public UserContext(IHttpContextAccessor httpContextAccessor)
+    {
+        _httpContextAccessor = httpContextAccessor;
+    }
+
+    public int UserId =>
+        int.Parse(
+            _httpContextAccessor.HttpContext?.User.Claims.FirstOrDefault(c => c.Type == ClaimTypes.NameIdentifier)
+                ?.Value ?? throw new UnauthorizedAccessException());
+}