Support discovery-based Firebolt connections

[kop]

Summary

• Add opt-in host/ssl_mode discovery connection options that fetch /.well-known/firebolt and route queries through the discovered endpoint.
• Preserve legacy auth/account/engineEndpoint routing while adding client-driven database, engine, and connection settings query parameters for discovery connections.
• Add unit coverage and a Core integration test for discovery-based connections.
• Update Core integration CI setup to install Firebolt through get.firebolt.io and expose FIREBOLT_HOST.

Verification

• npm run type-check
• npm test -- --coverage test/unit

Notes

• Local Core integration tests were not run in this workspace because Docker is not installed.

Linear Issue: FB-1830

  

[sonarqubecloud]

Quality Gate failed

Failed conditions
69.9% Coverage on New Code (required ≥ 80%)
27.1% Duplication on New Code (required ≤ 3%)

See analysis details on SonarQube Cloud