BSC LCLS: add bts-loop tests

Add basic establishment and teardown tests for 'bts-loop' mode of LCLS:
* add explicit vty init for desired LCLS kind
* add necessary IPA RSL MDCX functions
* explicitly pass LCLS kind as a parameter to shared
  functions (defaulting to 'mgw-loop')

Change-Id: I40e786b430591899c722d99d685db26efa868508
Related: OS#3659
diff --git a/bsc/BSC_Tests.ttcn b/bsc/BSC_Tests.ttcn
index 21ec0ff..13535ce 100644
--- a/bsc/BSC_Tests.ttcn
+++ b/bsc/BSC_Tests.ttcn
@@ -289,7 +289,7 @@
 	vc_MGCP.start(MGCP_Emulation.main(ops, mgcp_pars, id));
 }
 
-private function f_init_vty(charstring id := "foo") runs on test_CT {
+function f_init_vty(charstring id := "foo") runs on test_CT {
 	if (BSCVTY.checkstate("Mapped")) {
 		/* skip initialization if already executed once */
 		return;