CPS Delta API 1: Delta between 2 anchors

CPS Delta API 1: Delta between 2 anchors

- CPS Delta Feature Part 1: To find delta between two anchors
   - created new endpoint deltaByDataspaceAndAnchors
   - endpoint to take dataspaceName, source anchor, target anchor,
     xpath, descendants as input
   - added new service CpsDeltaService
   - added method to find delta between DataNodes:
     getDeltaReport
   - added method to find removed data nodes: getRemovedDeltaReports
   - added method to get Added DataNodes: getAddedDeltaReports
   - added method to get Map of xpath to DataNode: convertToXPathToDataNodesMap
   - added a POJO for delta report
   - Added new JSON data for delta feature testing
   - Added groovy test files CpsDeltaServiceImplSpec and DeltaReportBuilderSpec
   - code related to update operation, will be added in
     separate commit

Issue-ID: CPS-1824
Signed-off-by: Arpit Singh <as00745003@techmahindra.com>
Change-Id: I313f0f71d04b03878be7643f709d8af1aa6df6ba