Geo: Spike Self-Service Framework

What does this MR do?

Resolves #197319 (closed):

Goal

• Create a new PackageFile
• See that the secondary attempted to request the PackageFile
• See the PackageFileRegistry exists but failed

This cuts across the first implementation issues of &2346 (closed):

• #118743 (closed)
• #118745 (closed)
• #118749 (closed)
• #118747 (closed)

Not promised

• If a PackageFile is deleted, Geo may not send an event yet
• Existing PackageFiles are not synced
• Documentation
• All necessary tests
• Downloading a PackageFile may not work yet (Uploading to be implemented in another iteration)

Promised

• Feature flagged with geo_self_service_framework
• General architecture and naming
• It is clear where to add a Delete event
• It is clear where to add a new Blob Type so that it would also be synced upon creation

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

Tests will be added, however this is just the beginning of adding a new feature (Geo syncing of Package Files) and it will be feature flagged. Since the implementation is expected to be volatile for a few iterations, we only promise happy path feature specs in this iteration.