[ES|QL] Dense vector embedding function proof of concept

[afoucret]

This is a POC implementation for a function that allow to embed text as dense vector in ES|QL

TODO list:

• Implement the InferenceOperator
• Implement InferenceFunction
  • Basic function implementation (signature and parsing)
  • Add dimensions resolution for the Logical plam
• Implement logical and physical plan
  • Logical plan
  • Physical plan
  • Logical to physical mapping
  • Logical plan analysis
  • Logical plan optimization (Already implemented for all InferencePlan instances)
  • Physical planning
• Implement dense vector embedding function rewrite to a logical plan
• Implement foldable evaluation
• Implement inference resolution for function

Also missing (not in the scope of the POC):

• Tests
  • Unit
    • Analyzer, Logical plan optimization
  • Java REST and CSV tests
• Good documentation

Gaps:

• DENSE_VECTOR datatype does not support multivalued fields.

[github-actions]

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[github-actions]

🔍 Preview links for changed docs

• docs/reference/query-languages/esql/kibana/docs/functions/text_dense_vector_embedding.md