CPS-1586 Investigate implementation for persisting of top level list nodes

We are bringing support for persisting of top level list nodes. Here mainly it covers two issues, they are

1. Persisting list elements as a top level node creates multiple list nodes for every entry rather than a singular list node with the entries
2. Persisting a list element to a parent list 

• References
• Issues & Decisions

References

https://jira.onap.org/browse/CPS-1586

https://jira.onap.org/browse/CPS-358

Add support for persisting of top level list nodes

Issues & Decisions

{
  "bookstores":[
    {
      "bookstore-name": "Books"
    },
    {
      "bookstore-name": "Stories"
    }
  ]
}

[
  {
    "book-store:bookstores": {
      "bookstore-name": "Books"
    }
  },
  {
    "book-store:bookstores": {
      "bookstore-name": "Stories"
    }
  }
]

"book-store:bookstores": [
    {"bookstore-name":"Books"},
    {"bookstore-name":"Stores"}
]

Endpoint 

 POST 'http://localhost:8080/cps/api/v2/dataspaces/{dataspace-name}/anchor/{anchor-name}/nodes

 POST 'http://localhost:8080/cps/api/v2/dataspaces/{dataspace-name}/anchor/{anchor-name}/list-nodes

Required code Changes