Improve from/to wire RRSet conversion.

  • every "to/from wire" function... should be in the packet, rrset API shouldn't know anything about compression etc.
    • this is probably difficult, but the problem is this is one monolithic function, it could be like parser or state machine so you either give it a callback OR call it until it returns it has no more data to write, you could then receive a series of returns like "(DNAME, data, size), (FIXED, data, size)..." if you look at the wire_one, its mostly the same thing just the size is different and compression needs different treatment