Changes

ttcn3-asterisk: Add extra IP addr in ttcn3 docker for IMS Core

TTCN-3 docker container is emulating both the SIP UAs and the IMS Core.
So far all the components being emulated there were running under the
only local IP address available in the docker container.
This means, both the SIP UAs and the IMS Core were using the same IP
address.

This is actually causing problems for Asterisk, since on the VoLTE side
it needs to be configured to identify the endpoint based on the IMS Core
domain name.
Since the default identify matching ordered in Asterisk is:
"endpoint_identifier_order=ip,username,anonymous"
That means it always first checks the source IP address, which means
messages coming from local SIP UAs are misunderstood to be coming from
the IMS Core (since ims.mnc001.mcc238.3gppnetwork.org resolves to same
IP address).

The issue can be fixed by swapping the order to "username,ip", because
then the well-known 50X extensions are matched before attempting to
match by IP address.
However, this is all deviating config for the expected usual network
configuration, since the local IP network will be different than the IP
address coming from VoLTE.
Hence, let's instead properly separate the local SIP and VoLTE networks
with different IP addresses, which then solves the issue.

Change-Id: I6e5a261748ec61bb1cfa4aafee8c748d0f46aa9e