add f_vty_cfg_bts(), f_vty_cfg_msc()

These allow passing N vty configurations on the bts / msc node without
requiring subsequent 'exit'.

As an example, use f_vty_cfg_msc() in BSC_Tests.ttcn AMR config.

Change-Id: I9f3e485f692acb3d2a7620e9b454b372651be78e
diff --git a/library/Osmocom_VTY_Functions.ttcn b/library/Osmocom_VTY_Functions.ttcn
index a51794f..b291b03 100644
--- a/library/Osmocom_VTY_Functions.ttcn
+++ b/library/Osmocom_VTY_Functions.ttcn
@@ -174,6 +174,14 @@
 	f_vty_config2(pt, {config_node}, cmd);
 }
 
+function f_vty_cfg_bts(TELNETasp_PT pt, BtsNr bts := 0, rof_charstring cmds) {
+	f_vty_config3(pt, {"network", "bts " & int2str(bts)}, cmds);
+}
+
+function f_vty_cfg_msc(TELNETasp_PT pt, MscNr msc := 0, rof_charstring cmds) {
+	f_vty_config3(pt, {"msc " & int2str(msc)}, cmds);
+}
+
 function f_vty_transceive_match(TELNETasp_PT pt, charstring cmd, template charstring exp_ret) {
 	var charstring ret := f_vty_transceive_ret(pt, cmd);
 	if (not match(ret, exp_ret)) {