[Backport 3.0] [rule based autotagging] Add Get Rule API Logic

[opensearch-trigger-bot]

Backport 8932876 from #17336.

[andrross]

The 3.0 beta was the cutoff for new features, so I think we'll want to be pretty selective about what we merge into 3.0 at this point to ensure a stable release. This looks to me like much more of a new feature rather than a fix for a bug or performance issue. Is this critical to bring into 3.0 or can it be deferred until 3.1?

[github-actions]

✅ Gradle check result for ec03428: SUCCESS

[codecov]

Codecov Report

Attention: Patch coverage is 73.52941% with 54 lines in your changes missing coverage. Please review.

Please upload report for BASE (3.0@816787d). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
...va/org/opensearch/rule/rest/RestGetRuleAction.java	9.09%	30 Missing ⚠️
.../java/org/opensearch/rule/RuleFrameworkPlugin.java	42.85%	8 Missing ⚠️
...ule/service/IndexStoredRulePersistenceService.java	80.00%	4 Missing and 3 partials ⚠️
...rg/opensearch/rule/storage/XContentRuleParser.java	70.00%	3 Missing ⚠️
...arch/plugin/wlm/rule/WorkloadGroupFeatureType.java	77.77%	2 Missing ⚠️
...main/java/org/opensearch/rule/GetRuleResponse.java	95.00%	0 Missing and 1 partial ⚠️
...a/org/opensearch/rule/autotagging/FeatureType.java	0.00%	1 Missing ⚠️
...search/rule/storage/IndexBasedRuleQueryMapper.java	94.11%	0 Missing and 1 partial ⚠️
...wlm/rule/attribute_extractor/IndicesExtractor.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@          Coverage Diff           @@
##             3.0   #18055   +/-   ##
======================================
  Coverage       ?   72.58%           
  Complexity     ?    67152           
======================================
  Files          ?     5473           
  Lines          ?   309913           
  Branches       ?    45025           
======================================
  Hits           ?   224961           
  Misses         ?    66597           
  Partials       ?    18355           

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[jainankitk]

The 3.0 beta was the cutoff for new features, so I think we'll want to be pretty selective about what we merge into 3.0 at this point to ensure a stable release. This looks to me like much more of a new feature rather than a fix for a bug or performance issue. Is this critical to bring into 3.0 or can it be deferred until 3.1?

Thanks @andrross for bringing this up. While some of it is new feature, this PR has refactoring for moving autotagging logic into modules, which is the right place IMO. Hence, I would like to get this in to ensure we don't pollute core with stuff that is not needed!

[andrross]

While some of it is new feature, this PR has refactoring for moving autotagging logic into modules

@jainankitk This commit contains mostly new files. I don't see any files that have moved? Nevermind, I see now that some files moved from a lib to a module.

Hence, I would like to get this in to ensure we don't pollute core with stuff that is not needed!

I think you've accomplished that goal by committing this change to main. Why does this need to be backported into the release?

[kaushalmahi12]

This change should not be a breaking change since core functionality is still dorment (It is behind a plugin). Given we want to introduce the auto-tagging feature starting 3.0, I think it should be fine to put this in 3.0.

[jainankitk]

I think you've accomplished that goal by committing this change to main. Why does this need to be backported into the release?

I was hoping to make this change eagerly, but if you don't see any concerns with this happening in 3.1 instead of 3.0, I am fine with that.