Append and delete config (flows)

[indraniBh]

Enhancement

Model PR

Append or Delete flows in the config.
Implementation:

1. Append flows if the flow is not part of existing config
2. Delete flows which is part of existing config

Test cases:

1. Append config (validation): ensures the flows appended to be is not already part of existing configuration.
2. Append flows: Added multiple flows, if traffic is in starting state it will stop and apply traffic with newly added flows
3. Delete config (validation): Ensures the flows deleted to be should be part of existing configuration.
4. Delete config: Deleted multiple flows, if traffic is in starting state it will stop and apply delete flows

[alakendu]

I have left some comments. Please check.