OECDQuaterlyGDP | lint error fix

[Ashwani725]

The PR is raised to fix validation issue in OECDQuaterlyGDP. The Job is showing lint error that occur due to change in ref_area code changes in input source file To fix this, pv mapping is updated and added new ref_Area in it, Also raised a CL to add new stat vars.
Also added the Golden checks and tested them successfully.
Files added: manifest.json, pvmap.csv, golden_data/, validation_config.json
Test result: validation output

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[gemini-code-assist]

Code Review

This pull request introduces validation configuration and golden data files for the OECD quarterly GDP import. Specifically, it adds golden observation and summary report CSVs, registers the validation configuration in the manifest, ignores non-country regions ('EU' and 'EA') in the PV map, and defines validation rules in validation_config.json. The review feedback highlights a formatting issue with a misplaced closing brace and an inconsistent uppercase rule ID in the validation configuration.