[Metadata export]Add external features in analyzer

[yuli-han]

Summary

Add external features as enriched feature in analyzer to be exported to UMS

Why / Goal

Test Plan

• [x] Added Unit Tests
• [ ] Covered by existing CI
• [x] Integration tested

Added external feature: {"window":"","name":"ext_contextual_search_request_id","columnType":"string","operation":"","groupBy":"contextual_values","inputColumn":"search_request_id"}

Checklist

• [ ] Documentation update

Reviewers

@pengyu-hou @hzding621 @SophieYu41

[hzding621]

Could you also update line 334 - 344 to include schema for external parts?

[yuli-han]

Could you also update line 334 - 344 to include schema for external parts?

Hi @hzding621 The external features are included in the right schema.