in ran_msg, return gsm0808_speech_codec (intra-MSC)

Do not convert to enum mgcp_codecs, but directly pass the
gsm0808_speech_codec IE from the A interface to codecs handling.

For Iu:
- RAN side: use ran_infra.force_mgw_codecs_to_ran to keep the MGW
  endpoint towards RAN on IUFP.
- CN side: introduce flag ran_msg.assignment_complete.codec_with_iuup,
  so to decide whether to forward IUFP towards CN, we don't need to test
  the RAN type, but use the flag from the ran_msg implementation.

In msc_vlr_tests, use the SDP codec string instead of enum
mgcp_codecs.

So far limit to intra-MSC related messaging, adjusting inter-MSC
handover follows in a separate patch.

Change-Id: Ia666cb697fbd140d7239089628faed93860ce671
diff --git a/tests/msc_vlr/msc_vlr_test_call.c b/tests/msc_vlr/msc_vlr_test_call.c
index a547935..06602f7 100644
--- a/tests/msc_vlr/msc_vlr_test_call.c
+++ b/tests/msc_vlr/msc_vlr_test_call.c
@@ -227,7 +227,7 @@
 
 	btw("Assignment succeeds, triggering CRCX to CN");
 	expect_crcx(RTP_TO_CN);
-	ms_sends_assignment_complete(CODEC_AMR_8000_1);
+	ms_sends_assignment_complete("AMR");
 	OSMO_ASSERT(got_crcx);
 
 	btw("CN RTP address is available, trigger MNCC_RTP_CREATE");
@@ -339,7 +339,7 @@
 
 	btw("Assignment completes, triggering CRCX to CN");
 	expect_crcx(RTP_TO_CN);
-	ms_sends_assignment_complete(CODEC_AMR_8000_1);
+	ms_sends_assignment_complete("AMR");
 	OSMO_ASSERT(got_crcx);
 
 	btw("When the CN side RTP address is known, send MNCC_RTP_CREATE");
@@ -442,7 +442,7 @@
 
 	btw("Assignment completes, triggering CRCX to CN");
 	expect_crcx(RTP_TO_CN);
-	ms_sends_assignment_complete(CODEC_AMR_8000_1);
+	ms_sends_assignment_complete("AMR");
 	OSMO_ASSERT(got_crcx);
 
 	btw("When the CN side RTP address is known, send MNCC_RTP_CREATE");
@@ -539,7 +539,7 @@
 
 	btw("Assignment succeeds, triggering CRCX to CN");
 	expect_crcx(RTP_TO_CN);
-	ms_sends_assignment_complete(CODEC_AMR_8000_1);
+	ms_sends_assignment_complete("AMR");
 	OSMO_ASSERT(got_crcx);
 
 	btw("CN RTP address is available, trigger MNCC_RTP_CREATE");
@@ -635,7 +635,7 @@
 
 	btw("Assignment succeeds, triggering CRCX to CN");
 	expect_crcx(RTP_TO_CN);
-	ms_sends_assignment_complete(CODEC_AMR_8000_1);
+	ms_sends_assignment_complete("AMR");
 	OSMO_ASSERT(got_crcx);
 
 	btw("CN RTP address is available, trigger MNCC_RTP_CREATE");