TC_s1ap_attach: setup S11 interface, catch Create Session Request

The testcase TC_s1ap_attach is not complete yet. Since the testsuite
lacked the S11 interface, it was not possible to develop the testcase
beond the S1AP/NAS-EPS Security Mode Command. However, the S11 interface
is now available to the testsuite, so let's show that it works by
catching the Create Session Request. Let's also put a TODO that the
testcase needs to be completed still.

Related: OS#5760
Change-Id: I6350a3d5cab33fa4f43e4cdcbd7bf3241821d233
1 file changed