Add support for name compression to net/server.

[ximon18]

Currently the unstable server code under src/net/server uses StreamTarget<Target> everywhere.

To support DNS name compression it would need to support wrapping that in StaticCompressor, or for AXFR that should probably be TreeCompressor.

(on a semi-related note: StreamTarget is perhaps misnamed as it supports both datagram and stream targets)

[Philip-NLnetLabs]

We need to avoid hard coding MessageBuilder and leave it to a higher level message object to use a particular type of compression