epdg: Introduce test TC_hss_initiated_update_user_profile(_unknown)

This test so far only validates the SWx interface during the procedure.
It can be extended at a later time when implementing propagation of the
procedure to other interfaces in osmo-epdg.

Related: OS#6042
Change-Id: Ic7c19a3fe7b2b1411414fb6b78ab9a665a1aa42b
3 files changed