Add Classes Needed for Cross-Plugin Communication with SQL to a Common Library

[toepkerd]

Currently, plugins that want to integrate with the SQL plugin must pull in the entire SQL plugin's jar to retrieve a couple needed classes for communication with SQL plugin.

Examples:

• Alerting: https://github.com/opensearch-project/alerting/blob/93fcb58052aa40264fa3751c5b72c8508eddefa3/core/build.gradle#L21
• ML Commons (Skills): https://github.com/opensearch-project/skills/blob/edba19fcb01eaf444daad6cb3db7d271e33bca33/build.gradle#L84

This makes cross-plugin communication necessitate tight cross-plugin coupling. To loosen the coupling, SQL plugin can add classes that other plugins commonly use to a common library that is published to Maven for other plugins to pull instead of the entire SQL plugin jar.

Needed classes include:

• TransportPPLQueryAction
• TransportPPLQueryRequest
• TransportPPLQueryResponse

[github-actions]

Possible Duplicate

Found 1 possible duplicate issue(s):

• [FEATURE] Add transport API support for sql endpoint and add transport client library for invoking sql and ppl from other libraries. #2604

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