Figure out blueprint detection from tags. vs. main branch

[liamfallon]

Original issue URL: kptdev/kpt#3269
Original issue user: https://github.com/mortent
Original issue created at: 2022-05-27T21:52:25Z
Original issue last updated at: 2022-05-27T21:52:25Z
Original issue body: Should we:

• hide packages in main? (well, but they are there)
• not merge them into main at all? (this will likely not match customer expectation of branching/tagging in Git)
• or de-dupe identical packages? (in this case packages will pop up 'out of nowhere' when a duplicate blueprint is deleted but some of the dupes still remain)

We have already added functionality that tags the latest revision (kptdev/kpt#3015).

Original issue comments:

[liamfallon]

This is to do with a PackageRevision being created for main.

Blueprints:
When you approve, Porch commits the package to main and creates a tag. So there are two PackageRevision instances created, one for the tag and another for main.

We need to rethink how this works because this automatically created PackageRevision is confusing for users.

The discovery function should not rely on the main PackageRevision.

Deployment:

This PackageRevision is also used for deployment. The main PacakgeRevision may have been created for deployment.

[henderiw]

Here is the code related to this issue.

https://github.com/nephio-project/porch/blob/1754fc8fd09f799471d0916c50921b0b27aef50d/pkg/git/git.go#L262

[liamfallon]

Triaged
Triage Comment: Part of Porch rearchitecture