Fix Issue with Authenticated Proxies in Scrapy

[dream2333]

This pull request addresses an issue in Scrapy where authenticated proxies fail to connect.

Scrapy's proxy middleware automatically processes the HTTP Proxy-Authorization header, which needs special handling for authenticated proxies. To resolve this, special handling for authenticated proxies has been implemented, ensuring that the Proxy-Authorization header is correctly set in the request headers. The changes include:


1. Added logic to handle curl option and Proxy-Authorization in the handler.py file.
2. Ensured that the Proxy-Authorization header is properly set for proxy requests requiring user authentication.

These changes will fix the connection issues with authenticated proxies

[jxlil]

Thanks!