test: added test 579 to verify progress callback for chunked post

The 66 bytes checked are those 38 bytes with the chunked encoding
headers added: 8+8+10+35+5 = 66

The three-letter words become 8 bytes on the wire because they are sent
like: "3\r\none\r\n"

... and there's the trailing 5 bytes write after the four lines since
the final chunk is sent (which is "0\r\n\r\n").