Deploy CARP devd configuration via Salt

Summary:
Addt to the Salt state CARP the file /usr/local/etc/devd/carp.conf on router nodes.
This configuration allows devd to listen for CARP state changes (MASTER/BACKUP)
and automatically trigger the OVH failover script.

Ref T2276

Test Plan:

• Apply state on router-002:
  
  salt 'router-002' state.apply roles/router

• Apply state on router-003:
  
  salt 'router-003' state.apply roles/router

• sudo service devd restart

• Simulate failover of Master

• Test if the script is called

Reviewers: dereckson, Duranzed

Reviewed By: dereckson, Duranzed

Subscribers: Duranzed, dereckson

Maniphest Tasks: T2276

Differential Revision: https://devcentral.nasqueron.org/D4032