[coro_http][improve]Remove shared ptr, improve request ssl

[qicosmos]

Why

simplify request ssl, init_ssl is not necessary:

#ifdef CINATRA_ENABLE_SSL
  std::string uri = "https://cn.bing.com";
  auto data = co_await client.async_get(uri);
  std::cout << data.status << std::endl;
#endif

websocket client no need use shared_ptr any more.

add more examples.

What is changing

Example