Enable BBR config allowas-in 1 for internal peers
Why I did:
To advertise BBR routes learnt via e-BGP peer in one asic/namespace to another iBGP asic/namespace via Route Reflector.
* Initial commit for BGP internal neighbor table support.
> Add new template named "internal" for the internal BGP sessions
> Add a new table in database "BGP_INTERNAL_NEIGHBOR"
> The internal BGP sessions will be stored in this new table "BGP_INTERNAL_NEIGHBOR"
* Changes in template generation tests with the introduction of internal neighbor template files.