amarisoft_ue: Implement data plane

Use the ifup script to set up the netns + configure the tun device
created by lteue. Use it also as a hook to know when the UE is attached.
Since tun setup is done by arch-optimized lte-avx(2) binaries, we also
need to give capabilitites to them (instead of allowing inheritance of
caps in general in the setcap script).

Change-Id: I1e228b1296eac8e4cb183c2faa735b0468abe124
diff --git a/src/osmo_gsm_tester/templates/amarisoft_lteue.cfg.tmpl b/src/osmo_gsm_tester/templates/amarisoft_lteue.cfg.tmpl
index 59ab8b2..720c0ba 100644
--- a/src/osmo_gsm_tester/templates/amarisoft_lteue.cfg.tmpl
+++ b/src/osmo_gsm_tester/templates/amarisoft_lteue.cfg.tmpl
@@ -55,7 +55,7 @@
       //external_sim: true,
 
       /* Enable it to create a TUN interface for each UE PDN */
-      //tun_setup_script: "ue-ifup",
+      tun_setup_script: "${ue.ifup_filename}",
 
       sim_events: [{
         event: "power_on",