open5gs: Pre-configure tun device for UPF

open5gs requires the tun device to be pre-created and pre-configured
before using it. A ticket was opened in order to allow upfd itself
configuring it in [1]

[1] https://github.com/open5gs/open5gs/issues/899

Change-Id: I3b1857f09017cacee1c86f41dae1463c11b50490
diff --git a/utils/sudoers.d/osmo-gsm-tester_open5gs_tun_setup b/utils/sudoers.d/osmo-gsm-tester_open5gs_tun_setup
new file mode 100644
index 0000000..9b8ed83
--- /dev/null
+++ b/utils/sudoers.d/osmo-gsm-tester_open5gs_tun_setup
@@ -0,0 +1 @@
+%osmo-gsm-tester ALL=(root) NOPASSWD: /usr/local/bin/osmo-gsm-tester_open5gs_tun_setup.sh