esp_http_client: fixed http chunked encoding packet loss & add check data before...

esp_http_client: fixed http chunked encoding packet loss & add check data before read for ssl transport
- A bug of the http client when it downloads a chunked encoding packet is greater than the http_client's buffer, http_parser will call the callback body more than once, and the client will only handle the last
- with ssl_read, need to check before read to avoid timeout blocked when no data for reading