[Rule-based Auto Tagging] Add rule schema for auto tagging

[ruai0511]

Description

This PR introduces the schema for Rule object used in the auto tagging feature. A single rule will only have one feature but could have multiple attributes.
For the example below, the feature is query_group, and corresponds to the tag dev_query_group_id

{
    "_id": "fwhbuib397u4o03==",
    "description": "description",
    "attribute_1": ["logs123"],
    "attribute_2": ["xxxx", "yyyy"],
    "query_group": "dev_query_group_id",
    "updated_at": "01-10-2025T21:23:456Z"
}

Related issues:
RFC: #16797
#16813

Check List

• Functionality includes testing.
• API changes companion pull request created, if applicable.
• Public documentation issue/PR created, if applicable.

[github-actions]

✅ Gradle check result for f6a4a28: SUCCESS

[codecov]

Codecov Report

Attention: Patch coverage is 79.32692% with 43 lines in your changes missing coverage. Please review.

Project coverage is 72.36%. Comparing base (47d3655) to head (8f106ae).
Report is 7 commits behind head on main.

Files with missing lines	Patch %	Lines
...src/main/java/org/opensearch/autotagging/Rule.java	81.63%	6 Missing and 12 partials ⚠️
...java/org/opensearch/autotagging/RuleValidator.java	81.08%	4 Missing and 10 partials ⚠️
...ain/java/org/opensearch/autotagging/Attribute.java	45.45%	5 Missing and 1 partial ⚠️
...rg/opensearch/autotagging/AutoTaggingRegistry.java	83.33%	1 Missing and 2 partials ⚠️
...n/java/org/opensearch/autotagging/FeatureType.java	71.42%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #17238      +/-   ##
============================================
- Coverage     72.53%   72.36%   -0.18%     
+ Complexity    65826    65741      -85     
============================================
  Files          5311     5316       +5     
  Lines        305073   305281     +208     
  Branches      44243    44287      +44     
============================================
- Hits         221293   220912     -381     
- Misses        65688    66197     +509     
- Partials      18092    18172      +80     

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[github-actions]

✅ Gradle check result for 5c7de13: SUCCESS

[github-actions]

❕ Gradle check result for 108ae79: UNSTABLE

• TEST FAILURES:

      1 org.opensearch.snapshots.DedicatedClusterSnapshotRestoreIT.testSnapshotWithStuckNode
      1 org.opensearch.repositories.azure.AzureBlobStoreRepositoryTests.testIndicesDeletedFromRepository

Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.

[github-actions]

❕ Gradle check result for 8f106ae: UNSTABLE

• TEST FAILURES:

      2 org.opensearch.cluster.MinimumClusterManagerNodesIT.testThreeNodesNoClusterManagerBlock
      1 org.opensearch.snapshots.DedicatedClusterSnapshotRestoreIT.testSnapshotWithStuckNode

Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.

[sgup432]

LGTM! Thanks for making the change

[opensearch-trigger-bot]

The backport to 2.x failed:

The process '/usr/bin/git' failed with exit code 128

To backport manually, run these commands in your terminal:

# Navigate to the root of your repository
cd $(git rev-parse --show-toplevel)
# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add ../.worktrees/OpenSearch/backport-2.x 2.x
# Navigate to the new working tree
pushd ../.worktrees/OpenSearch/backport-2.x
# Create a new branch
git switch --create backport/backport-17238-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 b24c72b06bfd76d7d1d134a9ec9804965ad74352
# Push it to GitHub
git push --set-upstream origin backport/backport-17238-to-2.x
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/OpenSearch/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport/backport-17238-to-2.x.