config: ufw: enable firewall on boot, set log level to low

https://manpages.debian.org/buster/ufw/ufw.8.en.html

config/includes.chroot/etc/ufw/ufw.conf

@@ -0,0 +1,11 @@
+# /etc/ufw/ufw.conf
+#
+
+# Set to yes to start on boot. If setting this remotely, be sure to add a rule
+# to allow your remote connection before starting ufw. Eg: 'ufw allow 22/tcp'
+ENABLED=yes
+
+# Please use the 'ufw' command to set the loglevel. Eg: 'ufw logging medium'.
+# See 'man ufw' for details.
+LOGLEVEL=low
+