flowlib, flow: rename hw_flow to net_flow and update graph (take 2)

this commit is a bit over-loaded but I need to redo the
commits anyways.

Here we do a bunch or renaming, bring the messaging up to
speed with the kernel messaging and fix our handling of
graph types both put and get.

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>