feat(glean-backend): index all TechDocs-enabled Entities

[beejiujitsu]

Jira Ticket

N/A (I don't have access to your internal Notion/Jira)

Why

This is a large PR with a huge refactor / new features I spent months to make production ready.

What is changing

• feat: batch index all techdocs entities to Glean
• feat: regularly schedule indexing via config
• feat: configurable datasource
• fix getTechDocsMetadataUrl, getTechDocsStaticUrl 404 Not Found (wrong url!)
• feat: implement getTechDocsEntities using native backstage CatalogApi
• chore: migrate to new backend system
• chore: upgrade dependencies
• refactor: Service -> Client
• feat: GleanDocument, use entityUri for ID to prevent name collisions across different kinds
• style: Wealthsimple -> Company
• fix getTechDocsMetadataUrl, getTechDocsStaticUrl Unauthorized (use authentication)
• chore: lint

Checklist

• Reviewed the Checklist

How does this PR handle security?

Uses the native backstage AuthService for authenticating against frontend and backend services, where available.

config.d.ts properly marks entries that are secret as such, hiding them from the UI with plugins such as devtools.

Screenshot

Next steps