Extends the RetryAfterPlugin to support CORS. Closes #526 (#536)

Author: waldekmastykarz

dev-proxy-plugins/Behavior/RetryAfterPlugin.cs

@@ -106,6 +106,15 @@ private void UpdateProxyResponse(ProxyRequestArgs e, ThrottlingInfo throttlingIn
                 })
             );
         }
+        else
+        {
+            // ProxyUtils.BuildGraphResponseHeaders already includes CORS headers
+            if (request.Headers.Any(h => h.Name.Equals("Origin", StringComparison.OrdinalIgnoreCase)))
+            {
+                headers.Add(new("Access-Control-Allow-Origin", "*"));
+                headers.Add(new("Access-Control-Expose-Headers", throttlingInfo.RetryAfterHeaderName));
+            }
+        }
 
         headers.Add(new(throttlingInfo.RetryAfterHeaderName, throttlingInfo.ThrottleForSeconds.ToString()));