VTY: add osmo_tdef introspection and configuration commands

This change introduces several new VTY commands letting the user
a possibility to introspect and reconfigure some of the existing
timers implemented using libosmocore's osmo_tdef API.

At the moment this covers the following timers:

  - MGW specific timers:
    - X1 - MGCP response timeout,
    - X2 - RTP stream establishing timeout,

  - RAN specific timers (same names for GERAN and UTRAN):
    - X1 - Authentication and Ciphering timeout,
    - X2 - RAN connection release sanity timeout,
    - X3 - Handover procedure timeout.

The following commands are introduced:

  - 'enable' node:
    - show timer [(mgw|mncc|sccp|geran|utran|sgs)] [TNNNN]

  - 'config-msc' node:
    - timer [(mgw|mncc|sccp|geran|utran|sgs)] [TNNNN] [(<0-2147483647>|default)]

Both MNCC and SCCP related timer definitions are empty at the
moment. Achieved by using osmo_tdef_group API of libosmovty.

Change-Id: I6024c104b6101666c8aa1108a043910eb75db9a5
Related: OS#4368
diff --git a/src/libmsc/msc_vty.c b/src/libmsc/msc_vty.c
index 90cfc9d..53d44dc 100644
--- a/src/libmsc/msc_vty.c
+++ b/src/libmsc/msc_vty.c
@@ -36,6 +36,7 @@
 
 #include <osmocom/sigtran/sccp_helpers.h>
 
+#include <osmocom/vty/tdef_vty.h>
 #include <osmocom/vty/command.h>
 #include <osmocom/vty/logging.h>
 #include <osmocom/vty/misc.h>
@@ -716,6 +717,9 @@
 
 	neighbor_ident_vty_write(vty);
 
+	/* Timer introspection commands (generic osmo_tdef API) */
+	osmo_tdef_vty_groups_write(vty, " ");
+
 	return CMD_SUCCESS;
 }
 
@@ -2002,6 +2006,9 @@
 
 	neighbor_ident_vty_init(msc_network);
 
+	/* Timer configuration commands (generic osmo_tdef API) */
+	osmo_tdef_vty_groups_init(MSC_NODE, msc_tdef_group);
+
 	mgcp_client_vty_init(msc_network, MSC_NODE, &msc_network->mgw.conf);
 #ifdef BUILD_IU
 	ranap_iu_vty_init(MSC_NODE, (enum ranap_nsap_addr_enc*)&msc_network->iu.rab_assign_addr_enc);