Remove database access from the github webhook, use message passing instead

[jhrozek]

Summary

This is a large draft and I'm going to split it up. Manual testing works and I've been
adding/fixing tests and fixing various issues.

I will un-draft once I've finished testing, added unit tests for new code and the smoke tests passed locally.

• Remove unused setters of repoID attribute for entity reconciliation
• Use generic property keys instead of repoName/repoOwner when adding repos
• Add two more generic methods for EntityInfoWrapper
• Rename EntityWithProperties to EntityWithPropertiesByID
• Add EntityWithPropertiesByUpstreamID
• Add handler
• Use handler

Change Type

• Bug fix (resolves an issue without affecting existing features)
• Feature (adds new functionality without breaking changes)
• Breaking change (may impact existing functionalities or require documentation updates)
• Documentation (updates or additions to documentation)
• Refactoring or test improvements (no bug fixes or new functionality)

Testing

so far just manual that's why it's a draft.

Review Checklist:

• Reviewed my own code for quality and clarity.
• Added comments to complex or tricky code sections.
• Updated any affected documentation.
• Included tests that validate the fix or feature.
• Checked that related changes are merged.

[jhrozek]

I'm closing this PR in favor of opening smaller ones like #4565 which allow for better testing and easier rollback/revert if needed.