Created new metadata lib and added AliasMetadataModel and MappingMetadataModel classes

[gargmanik13]

Description

• Created a new library metadata under libs folder in the OpenSearch repo.
• This will help to separate out the metadata related dependencies which are currently coupled with cluster management dependencies in the server package. It'll make the Cluster Manager more cloud native provider friendly and help to eventually run the CM in stateless mode.
• As part of this change, added model classes for AliasMetadata and MappingMetadata which can be used independently and with existing OpenSearch dependencies to store relevant metadata.
• This PR will be followed by IndexMetadataModel class

Related Issues

Resolves #13197

Check List

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

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✨ Finishing touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment

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[github-actions]

❌ Gradle check result for aa3ee56: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[github-actions]

❌ Gradle check result for 47c27ce: FAILURE

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[github-actions]

❌ Gradle check result for 1bc5838: FAILURE

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[github-actions]

❌ Gradle check result for 5318259: FAILURE

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[gargmanik13]

❌ Gradle check result for 5318259: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

Test Result (2 failures / +1)
org.opensearch.repositories.azure.AzureBlobStoreRepositoryTests.testReadNonExistingPath
org.opensearch.indices.IndicesRequestCacheCleanupIT.testCacheCleanupWithDefaultSettings

Flaky tests:

• [AUTOCUT] Gradle Check Flaky Test Report for AzureBlobStoreRepositoryTests #14291
• [AUTOCUT] Gradle Check Flaky Test Report for IndicesRequestCacheCleanupIT #15822