Adding capability for remote search

[sstults]

Description

The Remote Query capability extends the Search Relevance plugin to execute search requests against external search systems (e.g., Solr or other OpenSearch clusters) while maintaining a consistent evaluation model. It introduces managed Remote Search Configurations with secure credential handling, per-config rate limiting and concurrency controls, and optional caching to reduce load and improve throughput. Queries are sent over HTTP(S) via a RemoteSearchExecutor, and results are normalized into an OpenSearch-compatible shape by the RemoteResponseMapper, enabling uniform processing regardless of the remote engine’s native response format. The system emphasizes robustness and observability with structured failure tracking, circuit breaker patterns, retries, and new metrics for remote execution performance, failures, and cache effectiveness.

This capability integrates with the existing experiment infrastructure. Experiments continue to use the same query sets, judgment workflows, and metrics (NDCG, MAP, MRR, P@K), and downstream evaluation remains unchanged because responses are normalized before scoring. The design supports side-by-side comparisons of local and remote systems within the standard experiment lifecycle, preserving backward compatibility while enabling cross-platform evaluation scenarios such as migration validation, A/B tests across environments, and multi-vendor benchmarking. This integration allows teams to compare configurations and engines under identical conditions, aggregate results using established indices and reports, and operate within familiar SRW orchestration, APIs, and persistence models.

Issues Resolved

List any issues this PR will resolve, e.g. Closes [...].

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 0.00%. Comparing base (4d08752) to head (bdeb196).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

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