- feat(middleware): added middleware what allow spiders to use the proxy from list;

[CESSIDY]

• Completed the development of ProxyRotationMiddleware - which makes it possible to use proxies from the proxy list;
• Implemented logic with a separate file for proxies;
• Adds an example file with proxies proxy_list.example.json;
• Added a description in middelware;
• Middleware works in two modes, with each request proxies are selected (1 - randomly, 2 - in order);