netipmid: consolidate message-related things in message.hpp

The message::Handler class was directly manipulating a bunch of stuff
on behalf of the message::Message class. This change moves more of the
changes into the message::Message class so it can manage its own data.

Change-Id: I5d31f6c3c5760207408238d048853e36a60c73e0
Signed-off-by: Vernon Mauery <vernon.mauery@linux.intel.com>
3 files changed