HDDS-15390. Utility to generate dependency ordered snapdiff report.

[SaketaChalamchala]

What changes were proposed in this pull request?

Developed with the help of Cursor AI.

This PR is intended as the foundation for a more efficient snapshot diff (HDDS-9154).

Baseline snapshot diff reports order entries by diff type (DELETEs first, then RENAME/CREATE/MODIFY). That ordering is not always safe to replay. For example, if A/B is renamed to C/B and directory A is deleted, replaying the DELETE before the RENAME fails on because the rename source no longer exists.
This PR adds isolated utilities for dependency-ordered snapshot diff report generation.

SnapDiffDependencyEntry

• Wraps a classified diff entry with objectId, parentObjectId, and the underlying DiffReportEntry
• Provides the metadata needed to build hierarchy and path-conflict edges

SnapDiffDependencyGraph

• Accepts a list of SnapDiffDependencyEntry values and builds a directed dependency graph in the constructor
• Applies these dependency rules defined via directed edges (u -> v means u must appear before v):
  • Parent CREATE/RENAME/MODIFY before child CREATE/RENAME/MODIFY
  • Child DELETE before parent DELETE
  • Non-delete entry before DELETE of its parent object
  • DELETE before CREATE/RENAME(target) that targets the same path
  • RENAME(source) before CREATE that targets the same path
• Exposes getOrderedEntries() using Kahn's algorithm
• Exposes static toOrderedReportEntries() to convert ordered dependency entries into DiffReportEntry payloads

What is the link to the Apache JIRA

https://issues.apache.org/jira/browse/HDDS-15390

How was this patch tested?

Unit Test.