Updated DG for network-topology-operation-activate

Following changes are included:
1) Handle l2 and l3 dci.
2) Handle 2 sites data keeping rest node template generic.
3) Fetch 3rd parth controller information using site-id.

Change-Id: I6d075cab2c7850197d91bd4e707c10c579458d48
Issue-Id: SDNC-104
Signed-off-by: Gaurav Agrawal <gaurav.agrawal@huawei.com>
Former-commit-id: 93b36edae1b14165ebd9c0fc9bbbe916c725790a