BE: Feature - Add support for nested field masking in Kafka UI.

[rdossantoslgc]

• Breaking change? (if so, please describe the impact and migration path for existing application instances)

What changes did you make? (Give an overview)
Problem Solved (Issue reported: #4361)
Previously, the masking feature only supported top-level field names. Users couldn't mask specific nested fields within complex JSON structures, leading to either over-masking (masking entire objects) or under-masking (missing sensitive nested data).

Features Added

1. Nested Field Path Support
   Dot Notation: Support for paths like user.email and etc
   Pattern Matching: Regex patterns now work with full field paths (e.g., ..secret.)
   Array Support: Handles arrays with indexed paths (e.g., users.0.email)
2. New Configuration Option
3. Backward Compatibility
   Default Behavior: enableNestedPaths defaults to false
   Existing Configs: All current masking configurations continue to work unchanged
   No Breaking Changes: API endpoints and data structures remain the same

Is there anything you'd like reviewers to focus on?

How Has This Been Tested? (put an "x" (case-sensitive!) next to an item)

• No need to
• Manually (please, describe, if necessary)
• Unit checks
• Integration checks
• Covered by existing automation

Checklist (put an "x" (case-sensitive!) next to all the items, otherwise the build will fail)

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (e.g. ENVIRONMENT VARIABLES)
• My changes generate no new warnings (e.g. Sonar is happy)
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged

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[github-actions]

Hello there rdossantoslgc! 👋

Thank you and congrats 🎉 for opening your first PR on this project! ✨ 💖

We will try to review it soon!

[Haarolean]

@rdossantoslgc this repo is no longer maintained (#4255), please refer to https://github.com/kafbat/kafka-ui

[rdossantoslgc]

Error being reported is to do with: fatal error: An error occurred (InvalidAccessKeyId) when calling the ListObjectsV2 operation: The AWS Access Key Id you provided does not exist in our records.

Not sure if this is something I can fix myself or the codeowners.