feat: FreeBSD and OpenBSD drivers, read side

FreeBSDDriver (`freebsd`) and OpenBSDDriver (`openbsd`) on a shared
BsdDriver, for the BSD VMs netOrk provisions and BSD hosts added by hand
(NetOrk/netork#798).

- SSH over exec channels (napalm-device-types' run_on_transport): no PTY,
  stdout and stderr apart, real exit codes; run_command()/open_stream()
  are public. Root through `sudo -S` with the password on stdin, or
  `sudo -n` without one.
- Facts: hostname, release and running kernel (freebsd-version / uname),
  hardware from SMBIOS (kenv) or hw.* sysctls, uptime from kern.boottime.
- Interfaces and addresses (ifconfig -a: ether/lladdr, hex netmasks,
  scoped IPv6), routes (netstat -rn, OpenBSD's abbreviated networks
  written out, host/broadcast/loopback entries left out), ARP (FreeBSD's
  sentences, OpenBSD's table), users and groups, processes (lstart read as
  one five-word field), cron jobs (system crontab and the login user's).
- Parsers are pure functions, tested on output recorded from FreeBSD 15.1
  (hand-installed and cloud image) and OpenBSD 7.9 (NetOrk/netork#793),
  with internal addresses replaced by documentation ranges.

tests/fixtures/openbsd-vm/netstat_an_f_inet.txt

@@ -0,0 +1,15 @@
+Active Internet connections (including servers)
+Proto   Recv-Q Send-Q  Local Address          Foreign Address        TCP-State
+tcp          0      0  10.0.2.15.22           10.0.2.2.53316         ESTABLISHED
+tcp          0      0  *.22                   *.*                    LISTEN
+tcp          0      0  127.0.0.1.25           *.*                    LISTEN
+Active Internet connections (including servers)
+Proto   Recv-Q Send-Q  Local Address          Foreign Address       
+udp          0      0  10.0.2.15.23532        93.241.86.156.123     
+udp          0      0  10.0.2.15.44456        162.19.170.154.123    
+udp          0      0  10.0.2.15.6243         162.159.200.1.123     
+udp          0      0  10.0.2.15.7949         24.134.7.185.123      
+udp          0      0  10.0.2.15.12367        168.119.211.223.123   
+udp          0      0  *.*                    *.*                   
+udp          0      0  *.*                    *.*                   
+udp          0      0  10.0.2.15.68           *.*