pkg-ubuntu: add build pipeline Ubuntu 22.04, 24.04

This commit add necessary files for building debian .deb package and
shell script to build for Ubuntu 22.04 and 24.04. You can use it by
running `extras/packaging/build_packages.sh` script.

Change-Id: I91ba97cbe932ff4207072dcb2f9d2b2887de236a
diff --git a/extras/packaging/gnu-linux/debian/dhtnet.postrm.debhelper b/extras/packaging/gnu-linux/debian/dhtnet.postrm.debhelper
new file mode 100644
index 0000000..71a29c2
--- /dev/null
+++ b/extras/packaging/gnu-linux/debian/dhtnet.postrm.debhelper
@@ -0,0 +1,19 @@
+# Automatically added by dh_installsystemd/13.6ubuntu1
+if [ "$1" = remove ] && [ -d /run/systemd/system ] ; then
+	systemctl --system daemon-reload >/dev/null || true
+fi
+# End automatically added section
+# Automatically added by dh_installsystemd/13.6ubuntu1
+if [ "$1" = "remove" ]; then
+	if [ -x "/usr/bin/deb-systemd-helper" ]; then
+		deb-systemd-helper mask 'dnc.service' >/dev/null || true
+	fi
+fi
+
+if [ "$1" = "purge" ]; then
+	if [ -x "/usr/bin/deb-systemd-helper" ]; then
+		deb-systemd-helper purge 'dnc.service' >/dev/null || true
+		deb-systemd-helper unmask 'dnc.service' >/dev/null || true
+	fi
+fi
+# End automatically added section