tcpdump: Log uid on pflog interfaces

If pf logs the user id ('pass out log (user)') have tcpdump also print
this.

Example output:
00:00:00.000000 rule 0/0(match) [uid 1001]: pass out on vtnet0: (tos 0x0, ttl 64, id 57539, offset 0, flags [none], proto UDP (17), length 55)

172.16.2.2.18337 > 172.16.2.1.53: [bad udp cksum 0x5c58 -> 0x16e4!] 40222+ A? google.be. (27)

PR: 122773
Differential Revision: https://reviews.freebsd.org/D17625