Extracted the user attr handling methods from ConfigModelV7 into its own class

[nibix]

Description

This code change is just in preparation for the change in #4380 as requested in https://github.com/opensearch-project/security/pull/4380#discussion_r1621324272 .

The code for user attribute handling is moved from the class ConfigModelV7 into its own class, as other new code will need to use it. Additionally, it enhances the structuring of the code by moving code with a specific purpose into its own class.

Personal note: A thorough re-design of this code might be worthwhile.

• Category: Refactoring
• Why these changes are required? New code introduced in #4380 needs to use this code.
• What is the old behavior before changes and new behavior after changes? No behavioral changes.

Issues Resolved

• https://github.com/opensearch-project/security/pull/4380#discussion_r1621324272

Is this a backport? If so, please add backport PR # and/or commits #

Testing

[Please provide details of testing done: unit testing, integration testing and manual testing]

Check List

• [ ] New functionality includes testing - no new functionality
• [ ] New functionality has been documented - no new functionality
• [x] Commits are signed per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license. For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 78.57143% with 6 lines in your changes missing coverage. Please review.

Project coverage is 65.45%. Comparing base (8688d6b) to head (4695280).

Additional details and impacted files

[](https://app.codecov.io/gh/opensearch-project/security/pull/4416?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=opensearch-project) ```diff @@ Coverage Diff @@ ## main #4416 +/- ## ========================================== + Coverage 65.42% 65.45% +0.02% ========================================== Files 310 311 +1 Lines 22013 22014 +1 Branches 3556 3556 ========================================== + Hits 14402 14409 +7 + Misses 5841 5836 -5 + Partials 1770 1769 -1 ``` | [Files](https://app.codecov.io/gh/opensearch-project/security/pull/4416?dropdown=coverage&src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=opensearch-project) | Coverage Δ | | |---|---|---| | [...pensearch/security/securityconf/ConfigModelV7.java](https://app.codecov.io/gh/opensearch-project/security/pull/4416?src=pr&el=tree&filepath=src%2Fmain%2Fjava%2Forg%2Fopensearch%2Fsecurity%2Fsecurityconf%2FConfigModelV7.java&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=opensearch-project#diff-c3JjL21haW4vamF2YS9vcmcvb3BlbnNlYXJjaC9zZWN1cml0eS9zZWN1cml0eWNvbmYvQ29uZmlnTW9kZWxWNy5qYXZh) | `67.92% <100.00%> (-0.47%)` | :arrow_down: | | [...opensearch/security/privileges/UserAttributes.java](https://app.codecov.io/gh/opensearch-project/security/pull/4416?src=pr&el=tree&filepath=src%2Fmain%2Fjava%2Forg%2Fopensearch%2Fsecurity%2Fprivileges%2FUserAttributes.java&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=opensearch-project#diff-c3JjL21haW4vamF2YS9vcmcvb3BlbnNlYXJjaC9zZWN1cml0eS9wcml2aWxlZ2VzL1VzZXJBdHRyaWJ1dGVzLmphdmE=) | `76.00% <76.00%> (ø)` | | ... and [5 files with indirect coverage changes](https://app.codecov.io/gh/opensearch-project/security/pull/4416/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=opensearch-project)