pf: add post-NAT src/dst address/port to pf_pdesc

[kp]

Summary

stuff nsaddr/ndaddr/nsport/ndport (addrs/ports after NAT, used a lot while
walking the ruleset and up until state is fully set up) into pf_pdesc instead
of passing around those 4 seperately all the time, also shrinks the argument
count for a few functions that have/partialy had an insane count of arguments.
kinda preparational since we'll need them elsewhere too, soon
ok ryan jsing

Obtained from: OpenBSD, henning <[e-mail]>, ccf63ac6cb
Sponsored by: Rubicon Communications, LLC ("Netgate")