Store properties for artifacts

[jhrozek]

Summary

• Add isOrg to the property wrapper signature - The wrapper for artifacts will call a different github provider call depending on whether we need to fetch an property for a user artifact or an organizational artifact. Let's extend the wrapper with a bool to allow that.
• Add property fetching for artifacts - Adds the properties that will be fetched and stored for artifacts as well as the wrapper fetching it.
• Use properties for artifacts in the github webhook - Amends the webhook code to refresh artifact properties in the webhook handler and store them for later use.

Fixes #4399

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

manual + make test. Will run the smoke tests

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.

[coveralls]

coverage: 53.066% (-0.2%) from 53.287%
when pulling 516052c on jhrozek:entity_artifact
into f6bff2f on stacklok:main.

[JAORMX]

LGTM, let's see if the local running of smoke tests agrees.

[jhrozek]

LGTM, let's see if the local running of smoke tests agrees.

I got failures in the PR tests because I was stupid and didn't rebase the artifact branch atop the recent PR fixes, but all other tests succeeded.