Make agent's entrypoint update agent's config on Windows
Make agent's entrypoint update agent's config on Windows

In future we will generate the whole config from scratch
as on Linux, but for now we only update the vhost's ifname.
It's the only field that can change upon restart.

Change-Id: Iec93bf6985295f9791b5a718c7b76cccaee7dacc
Depends-On: If99760bf0270be73a16197b62075bab7f1d0a023
Partial-Bug: #1806677

rombie/contrail-controller,rombie/contrail-controller,rombie/contrail-controller,rombie/contrail-controller,rombie/contrail-controller,rombie/contrail-controller,rombie/contrail-controller