Support infinitely long messages

Currently limited to `256 * 1024` in https://github.com/teragrep/rlo_06/blob/64bc07a81a5e7f4d466347316d874876b67f088e/src/main/java/com/teragrep/rlo_06/MsgFunction.java#L72C1-L72C43

RFC5424 does not define a limit for message length. Having a way to limit the maximum would be great to prevent accidental OoM scenarions