Signed-off-by: Jack.Zhang <hanyu.zly@alibaba-inc.com>

This commit adds a new test case.The new test case performs three
operations:

 install routes in vrf1.
 set redistribute vrf vrf1 command on vrf2.
 check the copying routes by vrf1 in vrf2.

Signed-off-by: Jack.Zhang <hanyu.zly@alibaba-inc.com>

    Example configuration:
        router bgp 100 vrf vrf-1
         address-family ipv4 unicast
          rd vpn export 1:1
          rt vpn both 1:1
          export vpn
          import vpn
          redistribute vrf vrf-2
         exit-address-family
         !
        !
        router bgp 100 vrf vrf-2
         neighbor 2.2.2.2 remote-as 1
         address-family ipv4 unicast
          rd vpn export 2:2
          rt vpn both 2:2
          neighbor 2.2.2.2 activate
         exit-address-family
         !
        !
    BGP routes learned from the neighbor 2.2.2.2 under VRF-1 can be directly copied to the BGP under VRF-1 without carrying the RD and RT attributes of VRF-1.
    After being copied to VRF-1, the routes will be sent to VPN with the RD 1:1 and RT 1:1 attributes, forming BGP-VPN routes.

Signed-off-by: Jack.Zhang <hanyu.zly@alibaba-inc.com>