pf: Introduce nvlist variant of DIOCADDRULE

This will make future extensions of the API much easier.
The intent is to remove support for DIOCADDRULE in FreeBSD 14.

Reviewed by: markj (previous version), glebius (previous version)
MFC after: 4 weeks
Sponsored by: Rubicon Communications, LLC ("Netgate")
Differential Revision: https://reviews.freebsd.org/D29557

(cherry picked from commit 5c62eded5a11ebdb1d57134d923596e2b04e9466)