bgpd: non pretty json output for neighbor routes

bgpd: non pretty json output for neighbor routes

Currently, json output of show BGP commands are no pretty format.

This is an extremely expensive operation for huge scale (lots of
routes with lots of paths).

BGP json non-pretty commands support added:

```
show bgp neighbors <nbr-id> advertised-routes json
show bgp neighbors <nbr-id> received-routes json
show bgp neighbors <nbr-id> advertised-routes detail json
show bgp neighbors <nbr-id> received-routes detail json
```

Ticket:#3513256
Issue:3513256

Testing: UT done

Signed-off-by: Sindhu Parvathi Gopinathan's <sgopinathan@nvidia.com>