Geo: Add PackageFileRegistryFinder to prepare for GraphQL API work

What does this MR do?

This will be used in !26719 (merged). It's split out to make more reviewable MRs.

Part of #199879 (closed)

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.