hlr: add tests for GSUP proxy routing

GSUP proxy routing, as it is implemented in an upcoming osmo-hlr patch,
requires that osmo-hlr returns a received Source Name IE back as Destination
Name IE. Add tests for these, for various situations.

These tests pass since GSUP request handling with request->response association
was introduced to osmo-hlr in I179ebb0385b5b355f4740e14d43be97bf93622e3.

Implement this by adding a source_name to the g_pars, which should be sent out
in ts_GSUP_* to osmo-hlr, and expected back as destination_name in returned
messages.

Add source_name and destination_name to various templates, with default :=
omit.

Add f_gen_ts_ies() and f_gen_tr_ies() to compose expected IEs more generically.

Change-Id: I3728776d862c5e5fa7628ca28d74c1ef247459fa
2 files changed