Add TCAP based loadsharing/routing

TCAP based loadsharing will share the load based on the TCAP oTID and
dTID.
Because TCAP are session based, a TCAP session based tracking is implemented,
to allow following traffic to forwarded to the same ASP.
This TCAP session tracking is similar to IP connection tracking.

ASPs within an AS can use the new IPA TCAP ROUTING protocol to register
for specific TCAP ranges.
TCAP sessions initiated by a peer (traffic towards such loadsharing AS/ASP),
will use the oTID of the `TCAP Begin` to loadshare and select a ASP.

Further if the TCAP session was initiated by a `loadshared` ASP, the oTID
will be added to the session tracking.

Co-authored-by: Harald Welte <laforge@osmocom.org>
Co-authored-by: Daniel Willmann <dwillmann@sysmocom.de>
Related: SYS#5423
Change-Id: Ibcb48aa0e515ad346f59ddd84b24c6e2c026144d
---
M examples/sccp_demo_user.c
M src/Makefile.am
M src/ipa.c
M src/m3ua.c
M src/ss7_as.c
M src/ss7_as.h
A src/ss7_as_loadshare_tcap.c
A src/ss7_as_loadshare_tcap.h
M src/ss7_as_vty.c
M src/ss7_asp.c
M src/ss7_asp.h
M src/ss7_internal.h
A src/tcap_transaction_tracking.c
A src/tcap_transaction_tracking.h
M src/xua_as_fsm.c
M stp/stp_main.c
M tests/tcap/Makefile.am
A tests/tcap/tcap_transaction_tracking_test.c
A tests/tcap/tcap_transaction_tracking_test.ok
M tests/testsuite.at
M tests/vty/osmo_stp_test.vty
21 files changed, 1,968 insertions(+), 14 deletions(-)