rc: finally deal with message of the day

Content follows, for now just use the sweet template Framework
to get this party started.

We're using "motd.in" so allow replacement during package builds.

plist

@@ -638,6 +638,7 @@
 /usr/local/opnsense/service/modules/template.py
 /usr/local/opnsense/service/run_unittests.py
 /usr/local/opnsense/service/templates/OPNsense/Auth/+TARGETS
+/usr/local/opnsense/service/templates/OPNsense/Auth/motd
 /usr/local/opnsense/service/templates/OPNsense/Auth/sshd.pam
 /usr/local/opnsense/service/templates/OPNsense/Auth/sudoers
 /usr/local/opnsense/service/templates/OPNsense/Captiveportal/+TARGETS

src/etc/rc

@@ -85,9 +85,6 @@ fi
 # regenerate groups and users for base
 /usr/local/etc/rc.recover base > /dev/null
 
-# rewrite message of the day
-/etc/rc.d/motd onestart
-
 # set keyboard map if needed
 /etc/rc.d/syscons onestart
 

src/opnsense/service/templates/OPNsense/Auth/+TARGETS

+motd:/etc/motd
 sshd.pam:/etc/pam.d/sshd
 sudoers:/usr/local/etc/sudoers.d/opnsense

src/opnsense/service/templates/OPNsense/Auth/motd.in

+Hello, this is OPNsense %%CORE_ABI%%.