gprs_ns2: rework IP-SNS binds

Introduce a `ip-sns-bind BINDID` vty command within a `nse` vty object.
The ip-sns-bind defines the binds which will be used by the dynamic
configuration with IP-SNS.
This is only the first part which only uses the binds when doing a
new SNS configuration.
The outgoing add procedure will be supported in a later patch
when the SNS fsm supports outgoing procedures.

This is a behaviour change of the API and must be synchronized with
the osmo-pcu. Otherwise SNS won't work with osmo-pcu.

Related: SYS#5354
Change-Id: I9ab8092bf286e7d90e92f5702a5404425e959c84
diff --git a/src/gb/libosmogb.map b/src/gb/libosmogb.map
index 699ed1b..588fabf 100644
--- a/src/gb/libosmogb.map
+++ b/src/gb/libosmogb.map
@@ -185,7 +185,9 @@
 gprs_ns2_recv_prim;
 gprs_ns2_reset_persistent_nsvcs;
 gprs_ns2_start_alive_all_nsvcs;
+gprs_ns2_sns_add_bind;
 gprs_ns2_sns_add_endpoint;
+gprs_ns2_sns_del_bind;
 gprs_ns2_sns_del_endpoint;
 gprs_ns2_vty_init;
 gprs_ns2_vty_init_reduced;