Preserve SiteOfOrigin when creating ServiceChain routes

Following changes are implemented:

- Infra for SiteOfOrigin (aka RouteOrigin) community
- ServiceChain changes to preserve SiteOfOrigin from original route

Change-Id: I9b26ed7ef148a5e367db5deb226bcaeafad44db3
Partial-Bug: 1383721
Merge "Preserve SiteOfOrigin when creating ServiceChain routes"