provide api readLineInto similar with asyncdispatch's recvInto
chronos provide readUntill raise two kinds of exception that I can handle, but when exception occurs I dont know how much bytes read , the parsing logic heavily relies on it.

https://github.com/bung87/looper/blob/b02e79c73b8cb6afd6e5231b632c1b2d9cdb60a0/src/looper/http/multipartparser.nim#L239-L246

https://nim-lang.org/docs/asyncdispatch.html#recvInto%2CAsyncFD%2Cpointer%2Cint