Part-2: Grouping of Data Nodes in Delta Report

Part-2: Grouping of Data Nodes in Delta Report

- Part two of new delta report format, proposed as an add-on feature to
  existing delta feature.
- Contains functionality of 'updated' and 'removed' delta report entries
  following the new Delta Report format
- The format for existing updated entries is modified as it is common
  between the two delta report formats
- A separate patch will be delivered in future to modify the format of
  existing delta report entries for added and removed data nodes to make
  it consistent with the new format.
- Documentation to Impacts and changes in old delta report format:
  https://lf-onap.atlassian.net/wiki/spaces/DW/pages/232194058/Proposed+changes+to+original+Delta+Report+Format

Issue-ID: CPS-2547
Change-Id: I489a5e8f0da7f012d5411870bccf886a987f600f
Signed-off-by: Arpit Singh <AS00745003@techmahindra.com>